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  • 51.
    Khartsev, Sergiy
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Bi3Fe5O12/Gd3Ga5O12 (m) magneto-optical photonic crystals2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 12Article in journal (Refereed)
    Abstract [en]

    A series of one-dimensional heteroepitaxial all-garnet magneto-optical photonic crystals has been synthesized and optically characterized. They are composed of alternating magneto-optically active Bi3Fe5O12 (BIG) and Gd3Ga5O12 (GGG) quarter-wave length layers pulsed laser deposited on to the GGG(001) substrate. Photonic crystals, as designed, exhibit stop band structure and the band gap with the transmittance central peak caused by the light localization in the half-wave length BIG cavity. Compared to previously reported [Bi3Fe5O12/Y3Fe5O12](m) photonic crystal [Appl. Phys. Lett. 84, 1438 (2004)], the replacement of optically dense Y3Fe5O12 garnet by transparent Gd3Ga5O12 enables significant enhancement of light rejection within the stop band. Photonic crystals spectra experience blue shift in oblique incidence geometry thus demonstrating feasibility to use this effect for tunable magneto-optical filters.

  • 52.
    Khartsev, Sergiy
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT).
    Heteroepitaxial Bi3Fe5O12/La3Ga5O12 films for magneto-optical photonic crystals2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, no 14Article in journal (Refereed)
    Abstract [en]

    Epitaxial La3Ga5O12 (LGG) garnet films and Bi3Fe5O12/La3Ga5O12 (BIG/LGG) heteroepitaxial film structures have been synthesized on the Gd3Ga5O12(GGG,111) single crystal. LGG films were grown by pulsed laser deposition technique whereas rf-magnetron sputtering was used to grow BIG films. LGG has a lattice constant 12.768 A that is bigger than that in GGG (12.384 A) and closer to that in BIG (12.626 A). We demonstrate feasibility of integration lanthanum gallium garnet with a giant Faraday rotator Bi3Fe5O12 in magneto-optical photonic crystals. Heteroepitaxial Bi3Fe5O12(1.9 mu m)/La3Ga5O12(300 nm)/GGG(111) structures show Faraday rotation as high as 5.74 deg/mu m compared to 5.46 deg/mu m in BIG/GGG at lambda=655 nm. Fitting LGG reflectivity spectra to Fresnel formulas yields LGG refractive index n(o)=1.981 compared to 1.963 in GGG at 655 nm. Dispersion of LGG refraction index follows Sellmeier formula n(o)(2)=1+2.77/[1-(143 nm/lambda)(2)] in the range from 400 nm to 1000 nm.

  • 53.
    Khartsev, Sergiy
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Andreasson, J.
    Koh, J. H.
    Song, J. S.
    Comparative characteristics of Na0.5K0.5NbO3 films on Pt by pulsed laser deposition and magnetron sputtering2003In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 55, p. 769-779Article in journal (Refereed)
    Abstract [en]

    Ferroelectric Na0.5K0.5 NbO3 (NKN) thin films were grown on the Pt 80 Ir 20 polycrystalline substrates by pulsed laser deposition (PLD) and radio frequency-magnetron sputtering (RF) technique using the same stoichiometric Na0.5K0.5NbO3 ceramic target. X-ray diffraction proved both PLD- and RF-made Na0.5K0.5 NbO3/Pt80Ir20 films are single phase and have preferential c -axis orientation. Temperature dependence of dielectric permittivity reveals the presence of two phase transitions around 210 and 410degreesC. Capacitance vs. applied voltage C-V @ 100 kHz, I-V , and P-E hysteresis characteristics recorded for the vertical capacitive structures yielded loss tandelta = 0.026 and 0.016, tunability about 44.5 and 30% @ 100 kV/cm, Ohmic resistivity 6.7 x 10(12) Omega.cm and 0.2 x 10(12) Omega.cm, remnant polarization 11.7 and 9.7 muC/cm(2) , coercive field 28.0 and 94.6 kV/cm for PLD- and RF-films, respectively. Piezoelectric test carried out in hydrostatic conditions showed piezoelectric coefficient d H = 21 for PLD-NKN and 15 pC/N for RF-NKN film.

  • 54.
    Khartsev, Sergiy
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Grishin, Michael A.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Characterization of heteroepitaxial Na0.5K0.5NbO3/La0.5Sr0.5CoO3 electro-optical cell2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, no 6, p. 062901-1-062901-3Article in journal (Refereed)
    Abstract [en]

    Heteroepitaxial Na0.5K0.5NbO3(1.5 mum)/La0.5Sr0.5CoO3(0.5 mum) (NKN/LSCO) films were grown on an Al2O3(0112) single crystal (r-cut sapphire) by rf-magnetron sputtering (NKN) and pulsed laser deposition (LSCO) techniques. Prism coupling waveguide refractometry has been employed to characterize vertical capacitive electro-optical cells with 2 X 8 mm(2) semitransparent Au top electrodes. Fitting reflectivity spectra to Fresnel formulas yields extraordinary and ordinary refractive indices n(e) = 2.232 and n(o) = 2.234 as well as electro-optic coefficient r(13) = 17.4 pm/V. Dispersion of the refraction index follows the Sellmeier formula n(2) = 1 + 3.46/[1-(244 nm/lambda)(2)] in the range from 400 nm to 850 nm.

  • 55.
    Khartsev, Sergiy
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Grishin, Michael A.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Heteroepitaxial Na0.5K0.5NbO3/La0.5Sr0.5CoO3 electro-optical cell2006In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 80, p. 133-143Article in journal (Refereed)
    Abstract [en]

    We report electro-optic performance of heteroepitaxial Na0.5K0.5NbO3(1.5 mu m)/La0.5Sr0.5CoO3 (0.5 mu m) (NKN/LSCO) films grown on Al2O3(01 (1) under bar2) single crystal (r-cut sapphire) by rf-magnetron sputtering (NKN) and pulsed laser deposition (LSCO) techniques. Vertical capacitive electro-optical cells were defined by a thermal evaporation of 2 x 8 mm(2) Au electrodes through the contact mask on top the NKN film. Processing parameters have been specially optimized to obtain electrosoftNKN films with a non-linear fatigue-free P-E characteristics: low remnant P-r = 7.7 mu C/cm(2) high induced polarization P = 23 mu C/cm(2) @ 400 km/cm , and the coercive field E-c = 70 kV/cm. Electro-optical characterization of NKN films has been performed using waveguide refractometry: a prism coupling of a light beam into the thin-film waveguide modes. Intensity of TM- and TE-polarized light of 655 nm laser diode reflected from the free surface of NKN film and Au-clad NKN/LSCO waveguide was recorded at zero and 15 V (100 kV/cm) bias electric field. Fitting reflectivity spectra to Fresnel formulas yields extraordinary and ordinary refractive indices n(c) = 2.232 and n(o) = 2.234 as well as electro-optic coefficient r(13) = 17.4 pm/V. Dispersion of the refraction index follows Sellmeier formula n(2) = 1+ 3.46/[1 + (244 nm/lambda)(2)] in the range from 400 nm to 850 nm.

  • 56.
    Khartsev, Sergiy
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Michael A.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Nilsson, Kenth
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Thin PZT film pressure microsensor2001In: Materials Research Society Symposium Proceedings, ISSN 0272-9172, E-ISSN 1946-4274, Vol. 666, p. F8121-F8126Article in journal (Refereed)
    Abstract [en]

    We report on a ferroelectric film pressure sensor fabricated on the top of 4 mm long and 1.4 mm in diameter Pt80Ir20 (PtIr) rod-shaped tip. It consists of a PZT(0.5 μm)/LSMO(0.1 μm) film heterostructure, deposited by pulsed laser ablation of stoichiometric ceramic targets PbZr0.52Ti0.48O3 and La0.67Sr0.33MnO3, and a circular, ∅ = 1.2 mm, Au electrode on the top of the PZT film. The Au/PZT/LSMO/PtIr thin-film capacitor demonstrates good ferroelectric properties: dielectric constant of 762 and loss tanδ =0.008 @ 5 kHz, induced polarization as high as 32 μC/cm2 at electric field of 250 kV/cm. Piezoelectric test, performed in a hydrostatic pressure chamber, exhibits the piezoelectric constant to be as high as 67 pC/N. This is 20% higher than 56 pC/N shown by a polarized bulk PZT sensor fabricated from the ceramics used as the target in the pulsed laser deposition process. Such an increase of the piezoelectric constant we attribute to the preferential (001) orientation of the PZT film grown on the PtIr bulk substrate. The resolution of the thin PZT film pressure microsensor was found to be about 1 mbar.

  • 57.
    Khartsev, Sergiy
    et al.
    KTH, Superseded Departments, Physics.
    Johnsson, P.
    Grishin, Alexander M.
    KTH, Superseded Departments, Physics.
    Colossal magnetoresistance in ultrathin epitaxial La0.75Sr0.25MnO3 films2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 87, no 5, p. 2394-2399Article in journal (Refereed)
    Abstract [en]

    We present results on magnetotransport measurements of a series of La0.75Sr0.25MnO3 films with thickness ranging from 32 to 3300 Angstrom. Films were fabricated using pulsed laser deposition onto SrTiO3 and LaAlO3 substrates. The substrate-film lattice mismatch causes strain in ultrathin films which diminishes with increasing thickness. Ultrathin films exhibit perfect match of in-plane film and substrate lattice parameters. The inhomogeneity of lattice parameters in thick films is caused by film-substrate mismatch strain and displayed by nonuniform broadening of x-ray diffraction Bragg reflections. The observation of characteristic Kiessig fringes is evidence for very uniform thickness of fabricated films. We found that the magnetotransport properties are strongly controlled by the film thickness and that allowed us to tailor the temperature of the metal-to-semiconductor phase transition in the range of 100-340 K with a change in magnetoresistivity within a factor of 3. We also present comparisons between the thickness dependence and oxygen deficiency in the films.

  • 58.
    Khartsev, Sergiy
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Kim, Joo-Hyung
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT).
    Integration of colossal magnetoresistors with GaAs2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 284, no 02-jan, p. 1-5Article in journal (Refereed)
    Abstract [en]

    Colossal magnetoresistive (CMR) La0.67Ca0.33MnO3 (LCMO) and La0.67Sr0.33MnO3 (LSMO) films have been grown by pulsed laser deposition technique on GaAs(001) substrates buffered with epitaxial MgO layer. X-ray diffraction revealed strong c-axis out-of-plane orientation and strong in-plane texture of CMR/MgO bilayers on GaAs single crystal. The maximum temperature coefficient of resistivity TCR = 9.0% K-1 at 223 K and 2.0% K-1 at 327 K. and the magnetoresistance Delta rho/rho similar to-7.95% kOe(-1) and -1.47% kOe(-1) have been achieved for LCMO/MgO/GaAs and LSMO/MgO/GaAs heteroepitaxial structures, respectively. Comparison with the test LCMO and LSMO films grown directly onto the bulk MgO(001) single cry tal demonstrates the identity of LSMO/MgO/GaAs and LSMO/MgO films properties whereas the LCMO films grown on MgO buffered GaAs show lower transition temperature T-c = 242 K compared to 253 K in LCMO/MgO.

  • 59.
    Kim, Joo-Hyung
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Epitaxial colossal magnetoresistive La-0.67(Sr,Ca)(0.33)MnO3 films on Si.2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 24, p. 4295-4297Article in journal (Refereed)
    Abstract [en]

    La-0.67(Sr,Ca)(0.33)MnO3 (LSCMO) films have been grown by a pulsed-laser deposition technique on Si(001) substrates buffered with Bi4Ti3O12/CeO2/yttrium-stabilized zirconia (YSZ) heteroepitaxial layers. X-ray diffraction has revealed cube-on-cube growth of an epitaxial Bi4Ti3O12/CeO2/YSZ/Si heterostructure whereas the LSCMO layer grows in the diagonal-on-side manner on top of the Bi4Ti3O12 (BTO) template. The maximum temperature coefficient of resistivity (TCR)=4.4% K-1 and colossal magnetoresistance (CMR) Deltarho/rhosimilar to2.9% kOe(-1) have been reached at 294 K. This was achieved due to the successive improvement of c-axis orientation of the layers: Full widths at half-maximum 0.65degrees, 0.58degrees, 0.65degrees, 1.13degrees, and 0.18degrees in LSCMO/BTO/CeO2/YSZ/Si stack, respectively. As a prototype of an uncooled bolometer, heteroepitaxial CMR structure on Si demonstrates, at 294 K, the noise equivalent temperature difference of 1.2 muK/rootHz@30 Hz.

  • 60. Koh, J. H.
    et al.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ferroelectric silver niobate-tantalate thin films2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 77, no 26, p. 4416-4418Article in journal (Refereed)
    Abstract [en]

    Submicron thick ferroelectric AgTa0.38Nb0.62O3 (ATN) films have been prepared by pulsed laser deposition technique onto Pt80Ir20 polycrystalline and La0.7Sr0.3CoO3/LaAlO3 single crystal substrates. ATN/Pt80Ir20 films have been found to be (001) preferentially oriented, while the epitaxial quality of ATN/La0.7Sr0.3CoO3/LaAlO3 heterostructures has been ascertained. Comparative analysis of the temperature and frequency dependencies of the dielectric permittivity epsilon' and loss tan delta in ATN films and bulk ceramics shows that in films: the coupled structural-ferroelectric monoclinic M-1-to-monoclinic M-2 phase transition occurs at the temperature 60 degrees lower than in ceramics, thus the temperature stability of epsilon' and tan delta in films is improved and occurs in extended temperature range. Reliable tracing of the ferroelectric hysteresis polarization versus electric loops indicates the ferroelectric state in ATN films at temperatures below 125 K and yields the remnant polarization of 0.4 muC/cm2 @77 K. Weak frequency dispersion, high temperature stability of the dielectric properties, as well as low processing temperature of 550 degreesC, are the most attractive features of ATN films.

  • 61. Koo, S. M.
    et al.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zetterling, Carl-Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Östling, Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ferroelectric Pb(Zr0.52Ti0.48)/SiC field-effect transistor2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 83, no 19, p. 3975-3977Article in journal (Refereed)
    Abstract [en]

    Nonvolatile operation of ferroelectric gate field-effect transistors in silicon carbide (SiC) is demonstrated. Depletion mode transistors have been realized by forming a Pb(Zr0.52Ti0.48)O-3/Al2O3 gate stack on n-type epitaxial channel layer and p-type substrate of 4H-SiC. A memory window, as wide as 5 V, has been observed in the drain current and the ferroelectric gate voltage transfer characteristics. The transistor showed memory effect from room temperature up to 200 degreesC, whereas stable transistor operation was observed up to 300 degreesC. The retention of remnant polarization was preserved after 2x10(4) s at 150 degreesC with no bias on the gate.

  • 62. Koo, S. M.
    et al.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zetterling, Carl-Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Östling, Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ferroelectric Pb(Zr,Ti)O-3/Al2O3/4H-SiC diode structures2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 5, p. 895-897Article in journal (Refereed)
    Abstract [en]

    Pb(Zr,Ti)O-3 (PZT) films (450 nm thick) were grown on 4H-silicon carbide (SiC) substrates by a pulsed-laser deposition technique. X-ray diffraction confirms single PZT phase without a preferred orientation. Stable capacitance-voltage (C-V) loops with low conductance (<0.1 mS/cm(2), tan deltasimilar to0.0007 at 400 kHz) and memory window as wide as 10 V were obtained when 5-nm-thick Al2O3 was used as a high band gap (E(g)similar to9 eV) barrier buffer layer between PZT (E(g)similar to3.5 eV) and SiC (E(g)similar to3.2 eV). High-frequency (400 kHz) C-V characteristics revealed clear accumulation, and depletion behavior. Although the charge injection from SiC is the dominant mechanism for C-V hysteresis in PZT/Al2O3/SiC, negligible sweep rate dependence and negligible applied bias dependence were observed compared to that of PZT/SiC. By using room-temperature photoilluminated C-V measurements, the interface states as well as the charge trapping in the PZT/Al2O3 stacks have been calculated.

  • 63. Koo, S. M.
    et al.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zetterling, Carl-Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Östling, Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Processing and properties of ferroelectric Pb(Zr,Ti)O-3/silicon carbide field-effect transistor2003In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 57, p. 1221-1231Article in journal (Refereed)
    Abstract [en]

    Metal-ferroelectric-(insulator)-semiconductor MF(I)S structures have been fabricated and the properties of pulsed laser-deposited PZT/Al-2 O-3 gate stacks have been studied on n - and p -type 4H-SiC. Among several polytypes of SiC, 4H-SiC is considered as the most attractive one because of its wider bandgap (E-g congruent to 3.2 eV) as well as higher and more isotropic bulk mobility than other polytypes. Single PZT phase without a preferred orientation was confirmed by x-ray diffraction. The interface trap densities N-IT , fixed oxide charges Q(F) , and trapped oxide charges Q HY have been estimated by C-V curves with and without photo-illuminated measurements at room temperature. It is found that the charge injection from SiC is the dominant mechanism for C-V hysteresis. Importantly, with PZT/Al-2 O-3 gate stacks, superior C-V characteristics with negligible sweep rate dependence and negligible time dependence under the applied bias were obtained compared to PZT directly deposited on SiC. The MFIS structures exhibited very stable capacitance-voltage C-V loops with low conductance (<0.1 mS/cm(2) , tan delta similar to 0.0007 at 400 kHz) and memory window as wide as 10 V, when 5 nm-thick Al2O3 was used as a high bandgap (E-g similar to 9 eV) barrier buffer layer between PZT (E-g similar to 3.5 eV) and SiC (E-g similar to 3.2 eV). The structures have shown excellent electrical properties promising for the gate stacks as the SiC field-effect transistors (FETs). Depletion mode transistors were prepared by forming a Pb(Zr-0.52 Ti-0.48 )O-3 /Al-2 O-3 gate stack on 4H-SiC. Based on this structure, ferroelectric Pb(Zr,Ti)O-3 (PZT) thin films have been integrated on 4H-silicon carbide (SiC) in a SiC field-effect transistor process. Nonvolatile operation of ferroelectric-gate field-effect transistors in silicon carbide (SiC) is demonstrated.

  • 64. Kucherenko, S. S.
    et al.
    Pashchenko, V. P.
    Polyakov, P. I.
    Khartsev, Sergiy
    Shtaba, V. A.
    The P-H-T effects on the electric resistance and magnetoresistance of La0.7Sr0.1Pb0.2MnO3 single crystal films2001In: Technical physics letters, ISSN 1063-7850, E-ISSN 1090-6533, Vol. 27, no 6, p. 451-453Article in journal (Refereed)
    Abstract [en]

    The effects of high hydrostatic pressures (P) and magnetic fields (H) in a broad temperature range (T = 77-325 K) on the electric resistance (R) and magnetoresistance (DeltaR/R-0) was studied in laser-deposited La0.7Sr0.1Pb0.2MnO3 single crystal films on (100)-oriented SrTiO3 substrates. A maximum response to the P and H variations was observed in the temperature interval of phase transitions (T = 310-325 K). A growth in the pressure P leads to an increase in both R and DeltaR/R-0 values, while an increase in the magnetic field strength H is accompanied by an increase in DeltaR/R-0 and a drop in the electric resistance R of the single crystal films studied.

  • 65.
    Linnarsson, Margareta K.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Primetzhofer, D.
    Possnert, G.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    ToF-MEIS stopping measurements in thin SiC films2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, p. 130-133Article in journal (Refereed)
    Abstract [en]

    Electronic stopping in thin, amorphous, SiC films has been studied by time-of-flight medium energy ion scattering and conventional Rutherford backscattering spectrometry. Amorphous SiC films (8, 21 and 36 nm) were prepared by laser ablation using a single crystalline silicon carbide target. Two kinds of substrate films, one with a lower atomic mass (carbon) and one with higher atomic mass (iridium) compared to silicon has been used. Monte Carlo simulations have been used to evaluate electronic stopping from the shift in energy for the signal scattered from Ir with and without SiC. The two kinds of samples are used to illustrate the strength and challenges for ToF-MEIS compared to conventional RBS.

  • 66.
    Linnarsson, Margareta K.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Wong-Leung, J.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy I.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Mn implantation for new applications of 4H-SiC2012In: Silicon Carbide and Related Materials 2011 / [ed] Devaty, RP; Dudley, M; Chow, TP; Neudeck, PG, Trans Tech Publications Inc., 2012, Vol. 717-720, p. 221-224Conference paper (Refereed)
    Abstract [en]

    Structural disorder and lattice recovery of high dose, manganese implanted, semiinsulating, 4H-SiC have been studied by secondary ion mass spectrometry, Rutherford backscattering in channeling directions, visible-to-near infrared optical spectroscopy as well as with transmission electron microscopy. After heat treatment at 1400 and 1600 °C, a substantial rearrangement of manganese is observed in the implanted region. However, the crystal has not been fully recovered. More disorder remains in the [1123] compared to the [0001] channel direction. Stacking faults, voids and 3C inclusions are observed in the implanted region. A Mn containing phase has most likely formed.

  • 67. Lisauskas, A.
    et al.
    Back, J.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Colossal magnetoresistive La-0.7(Pb1-xSrx)(0.3)MnO3 films for bolometer and magnetic sensor applications2001In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 89, no 11, p. 6961-6963Article in journal (Refereed)
    Abstract [en]

    We report on electrical and magnetic properties of a continuous series of solid solutions La-0.7(Pb1-xSrx)(0.3)MnO3 prepared by the pulsed laser deposition technique on LaAlO3 and SrTiO3 single crystals. Strict compositional control enables us to tailor the metal-to-semiconductor phase transition from 266 to 327 K, the maximum of temperature coefficient of resistance from 10.2% K-1 to 3.2% K-1, and maximum of magnetoresistance ratio at 7 kOe from 41% to 17% for x = 0 and x = 1 correspondingly. The ferromagnetic resonance linewidth ranges from 124 to 300 Oe, indicating low microwave loss and the films uniformity. Noise spectroscopy performed in the 2 Hz-20 kHz range reveals two components: Johnson noise (independent of frequency and bias current) and excess 1/f noise proportional to the square of the bias current. Very low excess noise (normalized value gamma /n varying in the range from 10(-20) to 10(-22) cm(3)) has been achieved due to the epitaxial quality of the fabricated films. Using these films, an infrared radiation bolometer and weak magnetic field sensor have been built and tested. The bolometer resolves the noise equivalent temperature difference as low as 120 nK/root Hz at 30 Hz frame frequency, while the magnetic field sensor shows the noise equivalent magnetic field difference of 50 mu Oe/root Hz at 1 kHz and optimum bias magnetic field applied.

  • 68. Lisauskas, A.
    et al.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Impedance fluctuations in epitaxial PZT films2001In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 38, no 04-jan, p. 647-656Article in journal (Refereed)
    Abstract [en]

    We report on measurements of impedance of Au/PZT/La0.67Sr0.33MnO3/Pt80Ir20 thin film capacitors performed in the time domain. Ferroelectric PZT films pulsed laser deposited on bulk polycrystalline Pt80Ir20 substrates demonstrate good ferroelectric properties: dielectric permittivity epsilon' = 880 and loss tandelta = 0.039 at 1 kHz, remnant polarization as high as 20 muC/cm(2), induced polarization of 40 muC/cm(3) at 380 kV/cm, and coercive field of 52.5 kV/cm. Resistivity of PZT film at coercive field was found to be 3.10(12) Omega.cm. Instantaneous C-V and I-V characteristics have been recorded to study the relaxation of polarization. Transient current exhibits non-Debye type relaxation, which has been nicely fitted to Curie-von Schweindler law j = j(leak) + j(o) (t/1sec)(-n) with an exponent nsimilar to0.8 while the power law C proportional to f(-0.1) has been found in frequency dispersion of the capacitance. Impedance fluctuation spectrum in the true leakage and resistance degradation regimes was found to follow 1/f(1.5) dependence. Close to breakdown field voltage fluctuations in ferroelectric capacitor increase, become non-steady randomly spike-shaped.

  • 69. Lisauskas, A.
    et al.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Tailoring the colossal magnetoresistivity: La-0.7(Pb0.63Sr0.37)(0.3)MnO3 thin-film uncooled bolometer2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 77, no 5, p. 756-758Article in journal (Refereed)
    Abstract [en]

    Epitaxial Ca, Sr, and Pb doped manganite films of various compositions and thickness have been prepared to tailor metal-to-semiconductor phase transition to room temperature. Continuous series of solid solutions La-0.7(Pb1-xSrx)(0.3)MnO3 grown by the pulsed laser deposition technique were found to possess superior performance regarding the maximum of temperature coefficient of resistivity (TCR) @300 K. In these films phase transition temperature T-c ranges from 266 to 327 K. We have engineered the film of the optimum composition x = 0.37 exhibiting the maximum of TCR = 7.4% K-1 @295 K. Relatively low excess noise (normalized Value gamma/n of 3 X 10(-21) cm(3)) has been achieved due to the epitaxial quality of the fabricated film. Using this film, infrared radiation bolometer demonstrator, operating at room temperature, has been built and tested. The bolometer resolves the noise equivalent temperature difference as low as 120 nK/root Hz and shows signal-to-noise ratio SNR = 8 X 10(6) root Hz/K, responsivity R = 0.6 V/W, detectivity D = 0.9 x 10(7) cm root Hz/W, and noise equivalent power NEP 3 X 10(-8) W root Hz at 30 Hz frame frequency. For micromachined thermally isolated La-0.7(Pb0.63Sr0.37)(0.3)MnO3 thin-film bolometer one can expect to get responsivity about 4 x 10(3) V/W and detectivity higher than 10(9) cm root Hz/W @30 Hz.

  • 70. Lyfar, D. L.
    et al.
    Ryabchenko, S. M.
    Krivoruchko, V. N.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Microwave absorption in a thin La0.7Sr0.3MnO3 film: Manifestation of colossal magnetoresistance2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 10Article in journal (Refereed)
    Abstract [en]

    Microwave (MW) absorption by a thin La0.7Sr0.3MnO3 film on a SrTiO3 substrate is investigated at a 9.1 GHz as a function of a dc magnetic field. Features of this absorption, namely, the jump in the absorption derivative, have been detected as the applied field passes through its zero value. Hysteretic behavior of the jumps is also observed. The results are discussed based on the model in which MW losses, additional to the ferromagnetic resonance, arise due to attenuation of MW currents induced in the sample by both variable magnetic induction and MW electrical field near the substrate surface with high dielectric permittivity. We show that zero-field anomalies in MW absorption are directly coupled with manganite magnetoresistive properties.

  • 71.
    Manuilov, Sergey A.
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Fors, Rickard
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Pulsed Laser Deposited Y3Fe5O12 Films for Magnetostatic Wave Band Pass Filters2009In: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 152-153, p. 377-380Article in journal (Refereed)
    Abstract [en]

    Y3Fe5O12 (YIG) films were pulsed laser deposited onto the Gd3Ga5O12(111) substrates. Processing conditions were optimized to obtain films with a narrow ferromagnetic resonance (FMR) linewidth: 0.9 Oe in 1.22 mu m thick YIG at 9 GHz. Due to sharp film-to-substrate interface YIG films remain strained hence possess unusually high lattice mismatch induced uniaxial anisotropy H-u = - 880 Oe. We fabricated and tested magnetostatic surface wave (MSSW) band pass hybrid-type filters with YIG film lain on transducers alumina board. MSSW filter with antennas areal size of 2 mm(2) at 7.5 GHz shows insertion loss - 9 dB and a resonant 3 dB bandwidth as narrow as 12.5 MHz.

  • 72.
    Manuilov, Sergey A.
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Fors, Rickard
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Submicron Y3Fe5O12 Film Magnetostatic Wave Band Pass Filters2009In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 105, no 3Article in journal (Refereed)
    Abstract [en]

    Thin Y3Fe5O12 (YIG) films were pulsed laser deposited onto Gd3Ga5O12 (111) and (001) substrates. Processing conditions were optimized to obtain compressively strained films with a ferromagnetic resonance linewidth at 9 GHz as narrow as 0.9 Oe and high uniaxial magnetic anisotropy H-u=-880 Oe. Several designs of magnetostatic surface wave (MSSW) bandpass filters were fabricated and tested: 0.45 and 0.22 mu m thick YIG films lain on transducers alumina board and with microstripe transducers defined directly onto YIG film, with effective antenna areal sizes of 2 and 0.4 mm(2). The MSSW filter with 2 mm(2) antenna shows, at 7.5 GHz, insertion loss -9 dB and a resonant -3 dB bandwidth as narrow as 12.5 MHz.

  • 73.
    Manuilov, Sergey A
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Pulsed laser deposited Y3Fe5O12 films: Nature of magnetic anisotropy I2009In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, no 12Article in journal (Refereed)
    Abstract [en]

    Recently we sintered by pulsed laser deposition (PLD) technique the epitaxial Fe-deficient yttrium iron garnet (YIG) films with ferromagnetic resonance (FMR) linewidth as narrow as 0.9 Oe, the uniaxial anisotropy as high as H-u=-880 Oe, and demonstrated them feasible for magnetostatic waves band pass filter application [Manuilov , J. Appl. Phys. 105, 033917 (2009)]. Here we explore the origin of unusually high noncubic magnetic anisotropy. Using the angular resolved FMR spectroscopy we found that in addition to strong uniaxial anisotropy, cubic magnetic anisotropy experienced almost fivefold reduction compared to standard YIG grown by liquid phase epitaxy. Molecular field theory was employed to calculate saturation magnetization 4 pi M-s, cubic magnetocrystalline K-1, and uniaxial anisotropy K-u in garnets with Fe vacancies. The modeling utilizes crystal field parameters that we revealed from earlier published experimental data on diamagnetic ion substituted Y3Fe5O12 and Fe-substituted isomorphous diamagnetic garnets. Consistent single ion anisotropy crystal field theory perfectly fits experimentally observed high saturation magnetization, reduction in cubic, and appearance of strong uniaxial anisotropy in PLD-grown Fe-deficient YIG films. The redistribution of Fe vacancies between different magnetic sublattices was quantified and confirmed that in YIG(111) films ferric ions preferentially leave vacant octahedrally coordinated sites. Simulation of growth induced anisotropy proves the ordering of Fe3+ vacancies within octahedral sites. At equal number of available ferric ions and vacancies, the latter populate the octahedrons with distortion axis perpendicular to the film surface with the probability equal to 0.67. Deformation blockage of octahedral complexes with distortion axes directed along the film surface reduces this probability down to 0.14.

  • 74. Markovich, V.
    et al.
    Jung, G.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Tsindlekht, M. I.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Yuzhelevski, Ya
    Gorodetsky, G.
    Magnetic separation and inelastic tunneling in self-doped manganite films2009In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, no 4Article in journal (Refereed)
    Abstract [en]

    Magnetic and transport properties of 100 nm thick La0.9MnO3-delta self-doped manganite films have been investigated in the temperature range 5-300 K. The films exhibit a paramagnetic to ferromagnetic transition at T-C = 194 K. The temperature dependence of the resistivity shows a metal-insulator transition at 204 K and a strong resistivity increase below 160 K. The magnetoresistance was always negative and slightly bias dependent. Variations in resistivity with magnetic field and current are nonhysteretic, while the temperature dependence of the resistivity exhibits unusual inverse thermal hysteresis. The magnetic field independent inverse thermal hysteresis is strongly influenced by a thermal history of the sample. The data suggest that nonlinear low temperature transport is dominated by inelastic tunneling through intrinsic tunnel junctions formed by phase-separated ferromagnetic metallic domains and insulating anti ferromagnetic matrix.

  • 75. Markovich, V.
    et al.
    Jung, G.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Tsindlekht, M. I.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Yuzhelevski, Ya
    Gorodetsky, G.
    Inverse thermal hysteresis and Peculiar Transport Properties of La(0.9)MnO(3-delta) film2010In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 200, p. 052014-Article in journal (Refereed)
    Abstract [en]

    Magnetic and transport properties of 100 nm thick La(0.9)MnO(3-delta) manganite films have been studied in the temperature range 5 - 300 K. The films exhibit a paramagnetic to ferromagnetic transition at T(C) approximate to 194 K. The temperature dependence of the resistivity shows a metal-insulator transition at 204 K and a strong resistivity increase at temperatures T < 160 K. Variations of resistivity with magnetic field and current are non-hysteretic, while the temperature dependence of the resistivity exhibits unusual inverse thermal hysteresis. The magnetic field independent inverse thermal hysteresis depends significantly on the thermal history of the sample. The data suggests that nonlinear transport characteristics are attributed to inelastic tunneling through intrinsic tunnel juctions formed by phase separated ferromagnetic metallic domains and insulating antiferromagnetic matrics.

  • 76. Medvedev, Y. V.
    et al.
    Nikolaenko, Y. M.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    The diagnostics of thermal kinetic coefficients for the optimization of film bolometer properties2002In: Technical physics, ISSN 1063-7842, E-ISSN 1090-6525, Vol. 47, no 1, p. 114-120Article in journal (Refereed)
    Abstract [en]

    A pulsed microwave technique for the fast and accurate diagnostics of a complete set of thermal kinetic coefficients in single-layer film structures is developed. The technique is tested on La-0.7(Pb0.7Sr0.3)(0.3)MnO3 films on LaAlO3 and SrTiO3 substrates-the structures featuring a temperature resistance coefficient of 5-7%, which is the highest for manganite-containing materials at room temperature. The results of numerical simulation show that the performance of the uncooled bolometers can be improved by optimizing the thermal conductivity of the substrate and matching the thermal resistances of the film-substrate and substrate-thermostat interfaces.

  • 77. Murzina, T. V.
    et al.
    Razdolski, I. E.
    Aktsipetrov, O. A.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Nonlinear magneto-optical effects in all-garnet magnetophotonic crystals2009In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 321, no 7, p. 836-839Article in journal (Refereed)
    Abstract [en]

    Nonlinear magneto-optical properties of all-garnet magnetophotonic crystals composed of alternating layers of ferromagnetic Bi3Fe5O12 ( BIG) and Sm3Ga5O12 quarter-wavelength layers with a half-wavelength BIG microcavity mode are presented. The samples are grown by rf-magnetron sputtering on non-magnetic GGG substrate. Many-fold enhancement of the magnetization-induced effects in second-harmonic generation (SHG) as compared with linear magneto-optical effects are observed: the SHG magnetic contrast up to 50% and magnetization-induced rotation of the polarization plane of about 901 are measured at the resonance microcavity wavelengh of lambda = 779 nm. (C) 2008 Elsevier B. V. All rights reserved.

  • 78. Pashchenko, V. P.
    et al.
    Shemyakov, A. A.
    Savosta, M. M.
    Khartsev, Sergiy
    Derkachenko, V. N.
    Prokopenko, V. K.
    Turchenko, V. A.
    Pashchenko, A. V.
    Dyakonov, V. P.
    Buhanzev, Y.
    Szymczak, H.
    Structural and magnetic inhomogeneity and the NMR of Mn-55 and La-139 in the magnetoresistive ceramics La0.7Ba0.3-xSnxMnO3 -> La0.7-xBa0.3-xMnO3+0.5xLa(2)Sn(2)O(7)2003In: Low temperature physics (Woodbury, N.Y., Print), ISSN 1063-777X, E-ISSN 1090-6517, Vol. 29, no 11, p. 910-916Article in journal (Refereed)
    Abstract [en]

    The effects of substitution of barium by tin on the phase composition, structural imperfection, and properties of lanthanum manganite perovskites La0.7Ba0.3-xSnxMnO3 (X=0, 0.1, 0.15, 0.2, 0.3) are established by comprehensive studies done by x-ray diffraction, resistive, and magnetic (including NMR on Mn-55 and La-139) methods. It is shown that the introduction of Sn leads to the formation of a pyrochloric phase La2Sn2O7, to an increase in the density of lattice defects of the manganese-enriched main lanthanum manganite phase, and to a substantial decrease of the magnetoresistive effect. The smearing of the metal-semiconductor phase transition temperature is explained by an increase in the inhomogeneity and imperfection of the perovskite structure. The low activation energy is confirmed by a high degree of inhomogeneity and imperfection of the crystal lattice of the samples studied. The broad, asymmetric NMR spectra of Mn-55 and La-139 attest to high-frequency electron exchange between Mn3+ and Mn4+ and nonequivalence of the environment of those ions and La3+ due both to heterovalent ions and to vacancies and clusters.

  • 79. Pashchenko, V. P.
    et al.
    Ul'yanov, A. N.
    Shemyakov, A. A.
    Khartsev, Sergiy
    Mezin, N. I.
    Medvedev, Y. V.
    Gusakov, G. V.
    Turchenko, V. A.
    Structure and properties of La0.6Sr0.4-xBaxMnO3 (0 <= x <= 0.4) magnetoresistive ceramics2002In: Inorganic Materials (Neorganicheskie materialy), ISSN 0020-1685, E-ISSN 1608-3172, Vol. 38, no 3, p. 302-307Article in journal (Refereed)
    Abstract [en]

    The effect of Ba content on the phase composition, lattice parameter, Mn-55 NMR spectrum, resistance, and magnetoresistance of La0.6Sr0.4-xBaxMnO3 perovskites was studied. The lattice parameter of the single-phase ceramic samples was found to increase with increasing x. The tolerance factor increases and the ionic field strength decreases as x increases from 0 to 0.4. The Mn-55 NMR results obtained at 77 K indicate a high-frequency electron exchange between Mn3+ and Mn4+ in the ferromagnetic phase. The peak-magnetoresistance temperature tends to decrease with increasing x. The magnetoresistance of the ceramics is correlated with the bond covalence. It is inferred that the ceramics contain inhomogeneities differing in nature and length scale (macroscopic, mesoscopic, and microscopic), which influence their magnetoresistance.

  • 80. Pohl, A.
    et al.
    Westin, G.
    Ottosson, M.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Fors, Rickard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Porous and dense perovskite films2008In: NANOSTRUCTURED MATERIALS AND NANOTECHNOLOGY / [ed] Mathur, S; Singh, M, 2008, Vol. 28, no 6, p. 153-163Conference paper (Refereed)
    Abstract [en]

    La0.5Sr0.5CoO3 (LSCO) and La 0.67Ca0.33MnO3 (LCMO) films were prepared by sol-gel techniques and their structural and transport properties investigated. Films were spin-coated onto (001) LaAlO3 (LAO), (001) SrTiO 3 (STO), Pt/TiO2/SiO2/Si, and Al 2O3 substrates, and heated to 800C. The structural properties were investigated using X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM). SEM studies showed that the films were crack-free and adhered well to the substrates. No preferential orientation of the perovskite films was observed on Si- or Pt/TiO2/SiO 2/Si-substrates, but films deposited on LAO and STO showed good alignment with the substrate. Transport measurements of epitaxial LCMO films show maximum temperature coefficient of resistivity (TCR) of 6.1% K-1 at 241 K and colossal magnetoresistance (CMR) of 32% at 246 K. The conductivity LSCO polycrystalline film was 1.7 mcm, while a epitaxial film had a conductivity of around 1.9 mcm.

  • 81. Razdolski, I. E.
    et al.
    Murzina, T. V.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Aktsipetrov, O. A.
    Magneto-optical switching in nonlinear all-garnet magnetophotonic crystals2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 16, p. 5600-5602Article in journal (Refereed)
    Abstract [en]

    Magnetic field control over the optical switching is demonstrated for a nonlinear all-garnet magnetophotonic crystal with a microcavity (MC) layer possessing both third-order Kerr nonlinearity and magnetooptical activity. A significant enhancement of the effective refractive index of the microcavity layer is observed, that results in the light-induced spectral shift of the MC mode of 2 nm. It is shown that application of the external magnetic field leads to an increase of switching contrast by a factor of two. Possible mechanisms of photorefractive effect involved in the optical switching in all-garnet magnetophotonic crystals are discussed.

  • 82. Schuisky, M.
    et al.
    Harsta, A.
    Khartsev, Sergiy
    KTH, Superseded Departments, Physics.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ferroelectric Bi4Ti3O12 thin films on Pt-coated silicon by halide chemical vapor deposition2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 88, no 5, p. 2819-2824Article in journal (Refereed)
    Abstract [en]

    A halide chemical vapor deposition technique has been developed to grow highly c-axis oriented submicron Bi4Ti3O12 films onto Pt(200 nm)/Ti(20 nm)/SiO2(1200 nm)/Si(100) substrates. BiI3, TiI4, and oxygen were used as precursors. The total gas pressure was found to be the critical processing parameter to grow films with good crystalline and dielectric properties. The 300 nm thick Bi4Ti3O12 films fabricated at 700 degrees C and total gas pressure of 3.8 Torr exhibit the best dielectric performance: dielectric constant around 200 and loss tan delta similar to 0.018 at 100 kHz, remnant polarization of 5.3 mu C/cm(2), induced polarization of 14.9 mu C/cm(2) at 560 kV/cm, coercive field of 150 kV/cm, electrical tunability of 51% at 350 kV/cm, resistivity of 2x10(9) Omega cm, and leakage current as low as 3x10(-5) A/cm(2) at 100 kV/cm. The effect of weak reduction of the remnant polarization and coercive field has been observed in the temperature range from 300 to 77 K and ascribed to the in-plane orientation of the polar a axis in fabricated Bi4Ti3O12 films.

  • 83. Shkar, V. F.
    et al.
    Denisenkov, V. P.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Yalali, A. A.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Nikolaev, E. I.
    Sayapin, V. N.
    A manifestation of magnetism of bismuth in iron garnet films2003In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 45, no 12, p. 2334-2337Article in journal (Refereed)
    Abstract [en]

    Bismuth iron garnet films prepared through electron-beam and laser-induced evaporation on (001)-oriented substrates of scandium gallium gadolinium garnet are investigated using ferromagnetic resonance. It is assumed that the additional minima observed in the angular dependence of the resonance field can be associated with the magnetic moment of bismuth ions.

  • 84. Shkar, V. F.
    et al.
    Nikolaev, E. I.
    Sayapin, V. N.
    Linnik, A. I.
    Denysenkov, V. P.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Structure and properties of deposited yttrium iron garnet films2005In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 47, no 6, p. 1107-1110Article in journal (Refereed)
    Abstract [en]

    Ferromagnetic resonance (FMR) and vibrating-sample magnetometer techniques were used to study the nature of the structural characteristics of yttrium iron garnet films deposited through either liquid phase epitaxy or laser evaporation on a (111)-oriented gallium gadolinium garnet substrate. It was proved that, based on the experimentally observed cubic magnetic anisotropy, deposited films should be considered to be single crystals. However, the absence of the FMR domain branch in a nonsaturated film and the shape of the magnetization curve indicate that a deposited film when demagnetized does not have a domain structure, as would be expected for a single-crystal film. According to the model proposed, a deposited film consists of close-packed single-crystal fragments with equal crystallographic orientation, the boundaries between which are in a partially atomically disordered state. As a result, such a film is both locally and macroscopically anisotropic, like a continuous single crystal. This film can split into domains only within a fragment (as is the case in a magnetic granular polycrystal); however, this does not happen, because the linear dimensions of a submicroscopic fragment are smaller than the equilibrium domain width.

  • 85. Tkatch, V. I.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Delayed nucleation in Fe40Co40P14B6 metallic glass2002In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 337, no 1-2, p. 187-193Article in journal (Refereed)
    Abstract [en]

    Metallic glass with a nominal composition of Fe(40)Co(40)P(14B)6 (numbers denote at.%) was prepared by the melt-spinning process. The as-quenched FeCo-based ribbons have good soft magnetic properties: the saturation magnetic polarization mu(0)M(s) = 1.45 T, a quasistatic coercive force of 4 A m(-1) and a maximum differential magnetic permeability of about 110 000 at 60 Hz. Fe40Co40P14B6 glass crystallizes by a eutectic reaction resulting in the face-centered cubic (f.c.c.) solid solution and the body-centered (b.c.) tetragonal (FeCo)(3)(PB) compound. The crystallization temperatures, determined using differential scanning calorimetry, are approximately 60 K higher than those for Fe40Ni40P14B6, Kolmogorov-Johnson-Mehl-Avrami model has been modified to account for temperature dependencies of nucleation and crystal growth rates and has been employed to quantify the non-isothermal glass crystallization process. Two fitting parameters: the activation energy of atomic transfer across crystal/glass interface Q and crystal/glass interfacial tension sigma, which govern crystal nucleation and growth, have been calculated from the set of experimental data of crystallization temperatures at different heating rates. While the estimated crystal growth rates in Fe40Co40P14B6 and Fe40Ni40P14B6 amorphous alloys are rather close, the homogeneous nucleation frequency in the FeCo-glass was found to be essentially lower than that in the FeNi-counterpart. It was concluded that a higher value of the crystal/glass interfacial tension a is responsible for enhanced thermal stability of the Fe40Co40P14B6 glass.

  • 86. Vanin, E. V.
    et al.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101).
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Material Physics, MF (Closed 20120101).
    Tarasenko, O.
    Johansson, Petter
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Broadband photoluminescence from pulsed laser deposited Er2O3 films2006In: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 121, no 2, p. 256-258Article in journal (Refereed)
    Abstract [en]

    Photoluminescence (PL) with the bandwidth of 45 nm (1523-1568 nm, at the level of 3 dB) was observed in amorphous Er2O3 films grown on to the quartz substrate by pulsed laser ablation of erbium oxide stoichiometric target. Optical transmission spectrum has been fitted to Swanepoel formula to determine the dispersion of refractive index and to extract resonance absorption peaks at 980 and 1535 nm. The maximum gain coefficient of 800 dB/cm at 1535 nm was estimated using McCumber theory and experimental spectrum of the resonance absorption. In 5.7mm-long waveguide amplifier a theory predicts the spectral gain of 20dB with 1.4dB peak-to-peak flatness in the bandwidth of 31 nm (1532-1563 nm) when 73% of Er3+ ions are excited from the ground state to the I-4(13/2) laser level. Strong broadband PL at room temperature and inherently flat spectral gain promise Er2O3 films for ultra-short high-gain optical waveguide amplifiers and integrated light circuits.

  • 87. Velichko, A.
    et al.
    Boriskov, P.
    Savenko, A.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Yar, Mazher Ahmed
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Memory resistive switching in CeO2-based film microstructures patterned by a focused ion beam2014In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 556, p. 520-524Article in journal (Refereed)
    Abstract [en]

    Heteroepitaxial CeO2 (80 nm)/La0.5Sr0.5CoO3 (500 nm) film structure has been pulsed laser deposited on a sapphire substrate. The Ag/CeO2 microjunctions patterned by a focused ion beam on a La0.5Sr0.5CoO3 film exhibit reproducible reversible switching between a high resistance state (OFF) with insulating properties and a semiconducting or metallic low resistance state (ON) with resistance ratios up to 10(4). The influence of micro-scaling and defects formed at the cell boundaries during etching on its electrical characteristics has been analyzed. The appearance of a switching channel at the moment of the electrical forming, responsible for the memory effect, has been proved, along with a mechanism of a self-healing electrical breakdown.

  • 88. Vieitez, M. O.
    et al.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Johnsson, P.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Electro-optic properties of heteroepitaxial Pb(Zr,Ti)O-3/La0.5Sr0.5CoO3 film structures2003In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 54, p. 607-618Article in journal (Refereed)
    Abstract [en]

    Vertical ferroelectric Pb(Zr,Ti)O-3 (PZT) 1 mum thick film capacitor was fabricated by pulsed laser deposition technique (PLD) onto conducting La-0.5 Sr-0.5 CoO3 (LSCO) 100 nm thick bottom electrode on both side polished YAlO 3 + 1% Nd2O3 (Nd:YAlO3) single crystal substrate to operate as a Pockels cell optical modulator. On top of the PZT film, semitransparent 30 nm thick Au electrode was deposited by thermal evaporation. Intensity of the chopped 670 nm polarized laser radiation transmitted through the Au/PZT/LSCO/Nd:YAlO3 cell was measured at various temperatures and bias voltage applied. Applying 20 V (200 kV/cm) across the capacitive cell, modulation of the transmitted light as high as 3% was achieved while the voltage tunability measured at 1 kHz from C - V characteristics was about 70%. Thermo-optical measurements performed for PZT/Nd:YAlO3 sample in the range up to 400degreesC showed the phenomenon of critical opalescence in the vicinity of Curie temperature at 208degreesC. Optical transmission through the PZT film biased with electric field was studied in the range 400 to 1000 nm. Film thickness, refraction index and absorption coefficient have been determined from the interference pattern observed in the PZT transmission spectrum. A simple model yields the dispersion relation for the electro-optic coefficient.

  • 89. Voloshin, V. A.
    et al.
    Gusev, A. A.
    Danilenko, I. A.
    Medvedeva, L. I.
    Prokhorov, A. D.
    Khartsev, Sergiy
    Interplay of structure, magnetism and resistivity of La0.5Ca0.54MnO3+x2000In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 271, no 02-jan, p. 121-127Article in journal (Refereed)
    Abstract [en]

    The structure of La0,5Ca0,5MnO3 is well known for T> 250 K and T( 150 K. But in the intermediate region some structure characteristics are difficult to understand [1]. This Letter studies in this temperature region the interrelation between structure and the experimental data like magnetism and resistivity on the basis of a vibron-electron dynamic equilibrium hypothesis. It has been shown that behavior of paramagnetic-to-ferromagnetic transition can be explaned in the framework of this hypothesis.

  • 90.
    Zhang, Zhigang
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ferroelectric properties of Na0.5K0.5NbO3 films at low temperatures2004In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 67, p. 59-68Article in journal (Refereed)
    Abstract [en]

    The temperature dependence of polarization and dielectric behaviour of Na0.5K0.5NbO3 thin films were studied from 25 K to room temperature. NKN films were deposited on Pt80Ir20 substrates by RF-magnetron sputtering. The freezing of domain walls with decreasing temperature makes domain walls switching difficult and suppresses the domain walls vibration. Both saturation remanent polarization and coercive field increased with decreasing the temperature. A pronounced low-temperature dielectric relaxation process was observed below 100 K; the relaxation rate fellows the Arrhenius law. Low temperature dielectric behaviour has been studied for the NKN films at various frequencies and bias electrical fields. Constant phase element model is introduced and can interpret the dielectric behaviour well. Dielectric constant, ac conductivity, loss tangent and universal law dielectric equation can be easily deduced from our model. The measured loss tangent and fitted result at various temperature and bias electrical fields agreed very well for our NKN films.

  • 91.
    Östling, Mikael
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Koo, S. M.
    Zetterling, Carl-Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ferroelectric thin films on silicon carbide for next-generation nonvolatile memory and sensor devices2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 469-70, p. 444-449Article in journal (Refereed)
    Abstract [en]

    Silicon carbide semiconductor technology has emerged as a very good candidate to replace traditional Si devices in special applications such as low loss power switching and high temperature electronics. Ferroelectric thin films exhibit interesting properties for use in semiconductor technology due to the spontaneous polarization which can be switched by an externally applied electric field, and thus are attractive for nonvolatile memory and sensor applications. In this work, the successful realization of ferroelectric thin films in SiC devices is described. The first experimental prototype devices are presented and discussed: A novel integration technique of junction metal-oxide-semiconductor field effect transistors (JMOSFETs) and nonvolatile FETs (NVFETs) on a single 4H-SiC substrate is presented. A constant current control device is based on the SiC JMOSFET. The drain current is effectively controlled and kept constant by a buried junction gate. A new high temperature SiC NVFET with a similar temperature stable current drive is also demonstrated. The nonvolatile memory device, based on the ferroelectric gate stack, was shown to operate up to 300 C with memory effect retained up to 200degreesC.

12 51 - 91 of 91
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