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  • 1. Ahlund, John
    et al.
    Nilson, Katharina
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Gothelid, Emmanuelle
    Schiessling, Joachim
    Göthelid, Mats
    Martensson, Nils
    Puglia, Carla
    Molecular growth determined by surface domain patterns2008Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, nr 17, s. 6887-6890Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The growth of iron phthalocyanine (FePc) on InSb(001) c(8 x 2) at submonolayer coverage has been investigated with scanning tunneling microscopy (STM). FePc adsorbs flat centered on the In rows both at 70 K and at room temperature (RT). However, the shapes of the two-dimensional molecular islands are fundamentally different; while the RT growth results in chainlike structures along the [I 10] direction, as already observed for other Pc's adsorbed on the same surface, the islands are prolonged along [110], i.e., perpendicular to the substrate rows, at 70 K. These observations are explained on the basis of a recently observed new surface phase at low temperature, resulting in structural domains on the surface. The molecular growth front follows the propagating domain boundary that freezes at low temperature.

  • 2.
    Ahmadi, Sareh
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Soldemo, Markus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Zuleta, Marcelo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Charge transfer and band bending on TiO2(110)-MgPcManuskript (preprint) (Annet vitenskapelig)
  • 3.
    Brena, Barbara
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Nilson, Katharina
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Agnarsson, Björn
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Önsten, Anneli
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Månsson, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    InSb-TiOPc interfaces: Band alignment, ordering and structure dependent HOMO splitting2009Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 603, nr 20, s. 3160-3169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin films of titanyl phthalocyanine (TiOPc) have been adsorbed on InSb(1 1 1) (3 x 3) and InSb(1 0 0) c(8 x 2) surfaces and studied with respect to their electronic structure using photoemission (PES), density functional theory (DFT) and scanning tunneling microscopy (STM). The interface chemical interaction is weak in both cases; no adsorbate induced surface band bending is observed and the energy level alignment across the interface is determined by the original position of the substrate Fermi level and the charge neutrality level of the molecule. Room temperature adsorption results in disordered films on both surfaces. The behaviors after annealing are different; on InSb(1 0 0) well-ordered molecular chains form along and on top of the In-rows, whereas on (1 1 1) no long range order is observed. The disorder leads to intermolecular interactions between the titanyl group and neighboring benzene rings leading to a split of TiOPc HOMO (highest occupied molecular orbital) by as much as 0.8 eV.

  • 4.
    Göthelid, Mats
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yu, S.
    Agnarsson, B.
    Önsten, A.
    Månsson, M.
    Brena, B.
    Charge transfer and band alignment at the InSb(111)B-TiOPc interfaceManuskript (Annet vitenskapelig)
  • 5.
    Nilson, K.
    et al.
    Department of Physics, Uppsala University.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Åhlund, J.
    Department of Physics, Uppsala University.
    Schiessling, J.
    MAX-laboratory, University of Lund.
    Göthelid, E.
    Department of Physics, Uppsala University.
    Mårtensson, N.
    Department of Physics, Uppsala University.
    Puglia, C.
    Department of Physics, Uppsala University.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    STM and XPS characterization of Zinc Phthalocyanine on InSb(001)2008Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 602, nr 2, s. 452-459Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Zinc phthalocyanine (ZnPc) adsorbed on the InSb(0 0 1)-c(8 x 2) surface has been studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Coverages from sub-monolayer to monolayer (ML) have been investigated. The molecules form ordered structures on the reconstructed rows of the surface with the molecular plane parallel to the surface. A change in the electronic structure between the sub-ML and higher coverages has been observed. Moreover, in order to study the influence of annealing on the electronic and geometric structures, the samples have been heated to elevated temperatures (about 640 K). In addition, multi-layer ZnPc films have been characterized by XPS measurements.

  • 6. Nilson, K.
    et al.
    Åhlund, J.
    Shariati, M. -N
    Schiessling, J.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Brena, B.
    Göthelid, E.
    Hennies, F.
    Huismans, Y.
    Evangelista, F.
    Rudolf, P.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Mårtensson, N.
    Puglia, C.
    Potassium-intercalated H2Pc films: Alkali-induced electronic and geometrical modifications2012Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 137, nr 4, s. 044708-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    X-ray spectroscopy studies of potassium intercalated metal-free phthalocyanine multilayers adsorbed on Al(110) have been undertaken. Photoelectron spectroscopy measurements show the presence of several charge states of the molecules upon K intercalation, due to a charge transfer from the alkali. In addition, the comparison of valence band photoemission spectra with the density functional theory calculations of the density of states of the H2Pc- anion indicates a filling of the formerly lowest unoccupied molecular orbital by charge transfer from the alkali. This is further confirmed by x-ray absorption spectroscopy (XAS) studies, which show a decreased density of unoccupied states. XAS measurements in different experimental geometries reveal that the molecules in the pristine film are standing upright on the surface or are only slightly tilted away from the surface normal but upon K intercalation, the molecular orientation is changed in that the tilt angle of the molecules increases.

  • 7. Nilson, Katharina
    et al.
    Åhlund, John
    Shariati, Masumeh-Nina
    Göthelid, Emmanuelle
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Schiessling, Joachim
    Berner, Simon
    Mårtensson, Nils
    Puglia, Carla
    Rubidium Doped Metal-Free Phthalocyanine Monolayer Structures on Au(111)2010Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, nr 28, s. 12166-12172Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Scanning tunneling microscopy (STM) studies of monolayer of metal-free phthalocyanine (H2Pc) adsorbed on Au(111) have shown ordered arrangement of the molecules on the surface. Evaporation of H2Pc onto the Au(111) surface and post annealing of the sample to 670 K results in a densely packed structure of the molecules. The monolayer is characterized by molecules adsorbed with the molecular plane parallel to the substrate surface in a square adsorption unit cell. Furthermore, the high resolution images revealed the orientation of individual molecules. The H2Pc/Au(111) system has also been doped by rubidum and compared to the undoped layers. The Rb affects the molecular adsorption geometry, and a hexagonal unit cell is found for the coadsorption of H2Pc and Rb. Upon doping, highly ordered Rb-induced protrusions are observed at the benzene site of adsorbed molecules.

  • 8.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Initial stages of metal- and organic-semiconductor interface formation2006Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This licentiate thesis deals with the electronic and geometrical properties of metal-semiconductor and organic-semiconductor interfaces investigated by photoelectron spectroscopy and scanning tunneling microscopy.

    First in line is the Co-InAs interface (metal-semiconductor) where it is found that Co is reactive and upon adsorption and thermal treatment it alloys with the indium of the substrate to form metallic islands, about 20 nm in diameter. The resulting broken bonds causes As entities to form which are loosely bond to the surface and evaporate upon thermal treatment. Thus, the adsorption of Co results in a rough interface.

    Secondly the metal-free phthalocyanine (H2PC) - titanium dioxide interface (organic-semiconductor) is investigated. Here it is found that the organic molecules arrange themselves along the substrate rows upon thermal treatment. The interaction with the TiO2 is mainly with the valence Π-electrons in the molecule causing a relatively strong bond, but this interaction is short range as the second layer of molecules retains their molecular character. This results in an ordered adsorption but limited mobility of the molecules on the surface prohibiting well ordered close packed layers. Furthermore, the hydrogen atoms inside the cyclic molecule leave the central void upon thermal treatment.

    The third case is the H2PC-InAs/InSb interface (organic-semiconductor). Here ordered overlayer growth is found on both substrates where the molecules are preferentially adsorbed on the In rows in the [110] direction forming one-dimensional chains. The InSb-H2PC interface is found to be weakly interacting and the bulk-like molecular character is retained upon both adsorption and thermal treatment. On the InAs-H2PC interface, however, the interaction is stronger. The molecules are more affected by the surface bond and this effect stretches up a few monolayers in the film after annealing.

  • 9.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Phthalocyanine interfaces: the monolayer region2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Organic molecules adsorbed on inorganic substrates are the topics of interest in this thesis. Interfaces of this kind are found in dye sensitized solar cells that convert solar energy to electricity, a promising environmentally friendly energy source which might provide a route to replace fossil fuels. Another field where these interfaces play a role is in molecular electronics, an approach to solve the down scaling in the ever increasing hunt for miniaturized electronic devices. The motivation for this work lies among other in these applications and surface science is a suitable approach to investigate the electronic and morphologic properties of the interfaces as it provides detailed knowledge on an atomic level.

    Phthalocyanines are the organic molecules investigated and the inorganic substrates range from wide band gap via narrow band gap semiconductors to metals. Photoelectron and X-ray spectroscopy experiments are performed to shed light on the electronic properties of the adsorbed molecules and the substrate, as well as the chemical interaction between adsorbate and substrate at the interface. The ordering of the adsorbate at the interface is important as ordered molecular thin films may have other properties than amorphous films due to the anisotropic electronic properties of the organic molecules; this is investigated using scanning tunneling microscopy.

    We find that the phthalocyanines are affected by adsorption when the substrate is TiO2 or Ag, where charge transfer from the molecule occurs or an interface state is formed respectively. The molecules are adsorbed flat on these surfaces giving a large contact area and a relatively strong bond. On Ag, ordered structures appear with different symmetry depending on initial coverage. The reactivity of the TiO2 surface is not ideal in the solar cell application and by modifying the surface with a thin organic layer, the negative influence on the adsorbed phthalocyanine is reduced. ZnO is not as reactive as TiO2, thanks maybe to the upright adsorption mode of the phthalocyanines. The semiconductor InSb is less reactive leading to self-assembled molecular structures on the (001) surface, either homogenously distributed in a one monolayer thick film or in strands along the reconstruction rows. InAs on the other hand has a larger influence on the adsorbed molecules resulting in a metallic film upon thermal treatment.

  • 10.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Angot, T.
    Nlebedim, Cajetan Ikenna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Layet, J. -M
    Le Lay, G.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ordered phthalocyanine superstructures on Ag(110)2008Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 128, nr 6, s. 064702-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic-metal interfaces, in particular, self-assembling systems, are interesting in the field of molecular electronics. In this study, we have investigated the formation of the Ag(110)-iron phthalocyanine (FePc) interface in a coverage range of less than 1 and up to 2 ML using synchrotron based photoelectron spectroscopy and low energy electron diffraction. As-deposited FePc forms a densely packed first layer exhibiting a 3x2/c(6x2) symmetry. Upon thermal treatment the order at the interface is modified depending on the initial FePc coverage, resulting in less densely packed but still ordered superstructures. The first monolayer is relatively strongly bound to the substrate, leading to the formation of an interface state just below the Fermi level. The highest occupied molecular orbital of FePc in the second layer is found at 1 eV higher binding energy compared to the interface state.

  • 11.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Angot, T.
    Nlebedim, Cajetan Ikenna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Layet, J.-M.
    Le Lay, G.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ordered phthalocyanine structures on Ag(110)2007Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690Artikkel i tidsskrift (Annet vitenskapelig)
  • 12.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Claesson, Thomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Önsten, Anneli
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Agnarsson, Björn
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Månsson, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Tjernberg, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Band bending and structure dependent HOMO energy at the ZnO(0001)-titanyl phthalocyanine interface2007Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 601, nr 18, s. 4222-4226Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have investigated the initial stages of titanyl phthalocyanine (TiOPc) growth on single crystalline ZnO(0 0 0 1). This organic-semiconductor interface is self-organizing as a 2 x 1 pattern appears in a low energy electron diffraction upon deposition of the molecules. To achieve this pattern, the TiOPc is suggested to adsorb standing with the edge of the molecule along the substrate atomic rows. Photoelectron spectroscopy is used to further analyze the interface; a relatively large upwards band bending amounting to 0.5 eV is found and a splitting of the molecules highest occupied molecular orbital occurs after thermal treatment, indicating that the molecules are lying down.

  • 13.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    Yu, S.
    Nilson, K.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Thermal effects on order at organic/inorganic interfaces: TiOPc on IOnSb(001)c(8x2)2007Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528Artikkel i tidsskrift (Annet vitenskapelig)
  • 14.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Nilson, K.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yu, S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Angot, T.
    Nlebedim, Cajetan Ikenna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Layet, J.-M.
    Le Lay, Guy
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Interface properties in organic thin films: FePc on TiO2(110)Inngår i: Journal of Physical Chemistry, ISSN 1932-7447Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Nilson, K.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    Angot, T.
    Nlebedim, Cajetan Ikenna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Layet, J. -M
    Le Lay, G.
    Götelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Strong interactions in dye-sensitized interfaces2008Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, nr 15, s. 5972-5977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phthalocyanines (Pcs) are capable of converting sunlight into electric energy when adsorbed on TiO2 in a dye-sensitized solar cell. Of special interest in this type of cell is the energy level alignment as well as how molecules adsorb on the surface as it determines the output of the cell. We investigated the FePc-TiO2(110) interface using scanning tunneling microscopy, synchrotron-based photoelectron spectroscopy, and X-ray absorption spectroscopy. We found a strong coupling of the first-layer FePc to the substrate resulting in an alteration of the electronic structure and charge transfer from the molecules. The FePc in the second layer is not severely affected by the bonding to the surface and has bulk-like electronic properties. The growth of FePc thin films proceeds in a layer plus island mode, and the molecular plane is parallel to the surface. The energy level alignment at the interface is determined, and the lowest unoccupied molecular orbital is found above the conduction band minimum of the oxide substrate.

  • 16.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Priya, Baskar Rao
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Niraj, N. Pio Peter
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Bonding of metal-free phthalocyanine to TiO2(110) single crystal2006Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 90, nr 20, s. 3602-3613Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The metal-free phthalocyanine interface formation on rutile TiO2(110) is investigated using scanning tunneling microscopy and photoelectron spectroscopy. The molecules are adsorbed flat on the surface, centered on the substrate oxygen rows. High-resolution core-level C1s spectroscopy indicates a strong difference between the second layer and the first monolayer bonding to the surface. The C1s core-level from the second layer has a bulk-like line shape whereas the first layer shows a strongly modified line profile. Upon thermal treatment, changes in the N1s core level line profile points to dehydrogenation of the center of the molecule.

  • 17.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Priya, Baskar Rao
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Niraj, N. Pio Peter
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Self-ordering of metal-free phthalocyanine on InAs(100) and InSb(100)2006Inngår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 18, nr 48, s. 10707-10723Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The adsorption and surface ordering of metal-free phthalocyanine (H2PC) on InAs(100)(4 x 2)/c(8 x 2) and InSb(100) c(8 x 2) is investigated using scanning tunnelling microscopy (STM) and synchrotron based photoelectron spectroscopy. The two systems show structural similarities; at submonolayer coverage the preferred adsorption site of H2PC is on top of the In rows, and above 1 monolayer and after thermal treatment the first molecular layer is ordered in a densely packed 'x3' structure observed with both low energy electron diffraction and STM.

    The electronic properties and the surface bonds of the two systems are quite different: the InAs-H2PC interface is semiconducting after room temperature adsorption but becomes metallic upon thermal treatment whereas InSb(100) H2PC is semiconducting at all preparations. These differences are reflected in pronounced differences in the C 1s line shape between the two systems. N 1s core level spectra from both surfaces reveal deprotonation of the molecules, i.e. the central hydrogen atoms are lost upon thermal treatment.

  • 18.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Szamota-Leandersson, Katolina
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Weissenrieder, Jonas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Claesson, Thomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Tjernberg, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Karlsson, Ulf O.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Chemical reaction and interface formation on InAs(111)-Co surfaces2005Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 574, nr 2-3, s. 181-192Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a study of the initial interface formation of Co on InAs(1 1 1)A and B surfaces using high resolution photoelectron spectroscopy and scanning tunneling microscopy. We observe a strong chemical interaction between Co and, in particular, surface indium forming a metallic overlayer already below monolayer coverage. On annealed surfaces this overlayer agglomerates into islands, with a narrow size distribution. Furthermore, no two-dimensional electron gas is formed on InAs(1 1 1)A-Co in contrast to the clean surface.

  • 19.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    MAX-lab., Lund University.
    Nilson, K.
    Department of Physics, Uppsala University.
    Åkermark, B.
    Organic Chemistry, Stockholm University.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Changing adsorption mode of FePc on TiO2(110) by surface modification with bipyridine2008Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 129, nr 7, s. 074707-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface modification of reactive oxide substrates to obtain a less strongly interacting template for dye adsorption may be a way to enhance performance in dye-sensitized solar cells. In this work, we have investigated the electronic and structural properties of 4,4(')-bipyridine (bipy) as modifier adsorbed on the TiO2(110) surface. The modified surface is then coated with iron phthalocyanine (FePc) and the properties of this heterostructure are investigated with synchrotron based photoelectron spectroscopy, x-ray absorption spectroscopy, and scanning tunneling microscopy. We find that a saturated monolayer consisting of standing bipy molecules with one nitrogen atom pointing outward is formed on the oxide surface. FePc adsorb in molecular chains along the [001] direction on top of bipy and ordered in a tilted arrangement with adjacent molecules partially overlapping. Already from the first layer, the electronic properties of FePc resemble those of multilayer films. FePc alone is oxidized on the TiO2(110) surface, but preadsorbed bipy prevents this reaction. The energy level lineup at the interface is clarified.

  • 20.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Åhlund, J.
    Nilson, K.
    Göthelid, E.
    Schiessling, J.
    Puglia, C.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Adsorption site of phthalocyanines on the InSb(001)c(8x2) surfaceManuskript (Annet vitenskapelig)
  • 21. Salomon, E.
    et al.
    Angot, T.
    Thomas, C.
    Layet, J. M.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Nlebedim, C. I.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Etching of silicon nanowires on Ag(110) by atomic hydrogen2009Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 603, nr 23, s. 3350-3354Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Scanning Tunnelling Microscopy, High Resolution Electron Energy Loss Spectroscopy and High Resolution X-Ray Photoelectron Spectroscopy have been used to study the adsorption of atomic hydrogen onto Si nanowires grown on Ag(1 1 0). We demonstrate that the hydrogen strongly interacts with the Si nanowires modifying their structural and electronic properties. Hydrogen atoms etch the Si nanowires and eventually lead to their complete removal from the Ag(1 1 0) surface.

  • 22.
    Szamota-Leandersson, Karolina
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Leandersson, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Karlsson, Ulf O.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Electronic structure of bismuth terminated InAs(100)2009Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 603, nr 1, s. 190-196Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deposition of Bi onto (4 x 2)/c(8 x 2)-InAs(1 0 0) and subsequent annealing results in a (2 x 6) surface reconstruction as seen by low electron energy diffraction. The Bi condensation eliminates the original (4 x 2) Surface reconstruction and creates a new Structure including Bi-dimers. This Surface is metallic and hosts a charge accumulation layer seen through photoemission intensity near the Fermi level. The accumulation layer is located in the bulk region below the surface, but the intensity of the Fermi level structure is strongly dependent oil the Surface order.

  • 23. Åhlund, J.
    et al.
    Nilson, K.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, E.
    Schiessling, J.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Mårtensson, N.
    Puglia, C.
    STM investigation of FePc on InSb(001)c8x2Manuskript (Annet vitenskapelig)
  • 24.
    Önsten, Anneli
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Stoltz, Dunja
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Claesson, Thomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Karlsson, Ulf O.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    SO2 interaction with Zn(0001) and ZnO(0001) and the influence of water2013Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 608, s. 31-43Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photoelectron spectroscopy has been used to study room temperature adsorption of sulfur dioxide on clean and water exposed (0001) surfaces of zinc and zinc oxide. Water has no significant effect either on clean or on SO2 exposed Zn(0001) at the low water pressures used (p < 10(-7) mbar). In the Case of the zinc-terminated ZnO(0001) surface, however, water adsorbs dissociatively and OH groups are shown to have a considerable effect on SO2 surface reactions. A strong oxidation reaction occurs between Zn(0001) and SO2 giving various sulfur containing species. On ZnO(0001), SO2 interacts mainly with oxygen sites giving SO3 or SO4 species. It is shown that the ZnO(0001) sample preparation procedure can have large effects on surface chemical and physical properties. Samples cleaned by four different preparation procedures are investigated, namely sputtering only and sputtering followed by annealing at 450 degrees C, 530 degrees C and 600-650 degrees C. Annealing at 600 degrees C leads to a transition from a partly OH-terminated surface to a triangularly structured surface free from OH groups. Adsorption of SO2 on the latter surface leads to a decreased surface conductivity, which hampers photoemission measurements. Water is shown to block SO2 adsorption sites on both 450 degrees C and 530 degrees C annealed samples. On the latter sample. SO2 reduction has been observed to a small extent on the clean surface and to a larger extent when the surface is prehydroxylated. Here, we speculate that water, similar to hydrogen, generates surface zinc clusters on ZnO(0001). Zinc clusters could enable charge transfer to the antibonding LUMO of the SO2 molecule and subsequent dissociation.

  • 25.
    Önsten, Anneli
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Stoltz, Dunja
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Claesson, Thomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Karlsson, Ulf O.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    SO2 Interaction with Zn(0001) and ZnO(0001) and the Influenceof WaterManuskript (preprint) (Annet vitenskapelig)
  • 26.
    Önsten, Anneli
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Stoltz, Dunja
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Karlsson, Ulf O.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Water Adsorption on ZnO(0001): Transition from Triangular Surface Structures to a Disordered Hydroxyl Terminated phase2010Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, nr 25, s. 11157-11161Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present room temperature scanning tunneling microscopy and photoemission spectroscopy studies of water adsorption on the Zn-terminated ZnO(0001) surface. Data indicates that the initial adsorption is dissociative leaving hydroxyl groups on the surface. At low water coverage, the adsorption occurs next to the oxygen-terminated step edges, where water is believed to bind to zinc cations leaving off hydrogen atoms to under-coordinated oxygen anions. When increasing the water dose, triangular terraces grow in size and pits diminish until the surface is covered with wide irregular terraces and a large number of small pits. Higher water exposure (20 Langmuir) results in a much more irregular surface. Hydrogen, which is produced in the dissociation reaction is believed to have an important role in the changed surface structure at high exposures. The fact that adsorbed water completely changes the structure of ZnO(0001) is an important finding toward the understanding of this surface at atmospheric conditions.

1 - 26 of 26
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