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Novel tantalate-niobate films for microwaves
KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Microwave materials have been widely used in a variety of applications ranging from communication devices to military satellite services, and the study of materials properties at microwave frequencies and the development of functional microwave materials have always been among the most active areas in solid-state physics, materials science, and electrical and electronic engineering. In recent years, the increasing requirements for the development of high speed, high frequency circuits and systems require complete understanding of the properties of materials function at microwave frequencies.

Ferroelectric materials usually have high dielectric constants, and their dielectric properties are temperature and electric field dependent. The change in permittivity as a function of electric field is the key to a wide range of applications. Ferroelectric materials can be used in fabrication capacitors for electronic industry because of their high dielectric constants, and this is important in the trend toward miniaturization and high functionality of electronic products. The simple tunable passive component based on ferroelectric films is a varactor which can be made as a planar structure, and electrically tunable microwave integrated circuits using ferroelectric thin films can be developed. Therefore, it is very important to characterize the dielectric constant and tunability of ferroelectric thin films.

This thesis shows experimental results for growth, crystalline properties and microwave characterization of Na0.5K0.5NbO3 (NKN), AgTa0.5Nb0.5O3 (ATN), Ba0.5Sr0.5TiO3 (BST) as well as AgTaO3 (ATO), AgNbO3 (ANO) thin films. The films were grown by Pulsed Laser Deposition (PLD) and rf-magnetron sputtering of a stoichiometric, high density, ceramic NKN, ATN, BST target onto single crystal LaAlO3(LAO), Al2O3 (sapphire), and Nd:YAlO3, and amorphous glass substrates. By x-ray diffractometry, NKN, ATN, BST films on LAO substrates were found to grow epitaxially, whereas films on r-cut sapphire substrates were found to be preferentially (00l) oriented.

Coplanar waveguide interdigital capacitor (CPWIDC) structures were fabricated by standard photolithography processing and metal lift-off technique. Microwave properties of the NKN/Sapphire and ATN/Sapphire with CPW structures were characterized using on-wafer microwave measurement technique. Measurement setup is composed of network analyzer, probe station, and microwave G-S-G probes. External electric field through the connection between network analyzer and power supply was applied to measure voltage tunability. Measured S-parameter were used for the calculation of capacitance, loss tanδ, tunability and K-factor.

The NKN films interdigital capacitors with 2 μm finger gap on Nd:YAlO3 showed superior performance compared to ATN in the microwave range from 1 to 40 GHz. Within this range, the voltage tunability (40V, 200 kV/cm) was about 29%, loss tangent ∼ 0.13, K-factor = tunability/tanδ from 152% @ 10GHz to 46% @ 40GHz.

The microwave performance of ATN film CPWIDC with 2 μm finger gap on sapphire substrate in the microwave range from 1 to 40 GHz showed that frequency dispersion is about 4.3%, voltage tunability was 4.7% @ 20GHz and 200 kV/cm, loss tangent ∼ 0.068 @ 20GHz, K-factor = tunability/tanδ is ranged from 124% @ 10GHz to 35% @ 40GHz.

The BST films CPWIDC with 2μmfinger gap on Al2O3 substrate showed frequency dispersion of capacitance in the microwave range from 1 to 40 GHz about 17%, voltage tunability = 1 - C(40V)/C(0) ∼ 22.2%, loss tangent ∼ 0.137 @ 20GHz, and K-factor = tunability/tanδ from 281% @ 10GHz to 95% @ 40GHz.

Place, publisher, year, edition, pages
Stockholms: KTH , 2005. , viii, 40 p.
Series
Trita-EKT, ISSN 1650-8599 ; 2005:4
Keyword [en]
ferroelectrics, sodium potassium niobates, silver tantalate niobate, barium stronitium titanate
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-489OAI: oai:DiVA.org:kth-489DiVA: diva2:14197
Presentation
2005-10-28, C4, Electrum, 10:00
Opponent
Supervisors
Note
QC 20101207Available from: 2005-11-11 Created: 2005-11-11 Last updated: 2010-12-07Bibliographically approved
List of papers
1. Na0.5K0.5NbO3 film microwave varactors
Open this publication in new window or tab >>Na0.5K0.5NbO3 film microwave varactors
2004 (English)In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 66, 291-300 p.Article in journal (Refereed) Published
Abstract [en]

Na0.5K0.5NbO3 (NKN) and Pb(Zr 0.53Ti0.47)O3 (PZT) films have been grown by rf-magnetron sputtering and pulsed laser deposition techniques, correspondingly, on sapphire (Al2O3-0112, r-cut), quartz (Y + 36°-cut) and YAlO3 + 1%Nd(Nd:YAlO3-001) single crystal substrates with Interdigital Capacitor (IDC) of Coplanar Waveguide (CPW) structure. Photolithography and metal lift-off technique was used for processing of the tunable microwave capacitor. Microwave network analyzer with G-S-G Picoprobe and probe station performed microsvave measurement with external DC bias. NKN film interdigital capacitors on Nd:YAlO3 show superior performance in the microwave range from 1 to 40 GHz. Within this range, the voltage tunability (40 V, 200 kV/cm) was about 29%, loss tangent ∼0.13, K-factor from 152% @10 GHz to 46% @40 GHz, voltage independent Cp was about 230 fF, tan δp changes from 0.14 @ 10 GHz to 0.36 @40 GHz, real and imaginary part of interconnect impedance increases with frequency from 0.13 Ω@ 10 GHz to 0.50 Ω @40 GHz and from 1.9 Ω@10 GHz to 5.9 Ω @40 GHz respectively.

Keyword
Coplanar waveguide, Interdigital capacitor, Network analysis, Pulsed laser deposition, rf-magnetron sputtering, Thin ferroelectric NKN films
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-6584 (URN)10.1080/10584580490895752 (DOI)000226089700031 ()2-s2.0-33646699867 (Scopus ID)
Note
QC 20100906Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2017-12-14Bibliographically approved
2. Processing and on-wafer test of ferroelectric film microwave varactors
Open this publication in new window or tab >>Processing and on-wafer test of ferroelectric film microwave varactors
2006 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Applied physics letters, Vol. 88, no 19, 192905- p.Article in journal (Refereed) Published
Abstract [en]

We present comparative characteristics of microwave variable capacitors (varactors) fabricated on Na0.5K0.5NbO3 (NKN), AgTa0.5Nb0.5O3 (ATN), and Ba0.5Sr0.5TiO3 (BST) ferroelectric films grown by rf-magnetron sputtering (NKN) and pulsed laser deposition (ATN and BST) techniques on the sapphire. Two port 2 mu m finger gap coplanar waveguide interdigital capacitors (CPWIDCs) were defined on ferroelectric films surface by photolithographic lift-off technique. Deembedding method was employed to extract properties of CPWIDC from the S parameters measured in microwave range up to 40 GHz. BST films on sapphire substrates show superior tunability of 26% (20 GHz, 200 kV/cm), whereas ATN films possess the lowest tan delta=0.06 at 20 GHz and extremely low dispersion of 4.3% in a whole frequency range of 45 MHz-40 GHz.

Keyword
Capacitors, spectra
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-6578 (URN)10.1063/1.2202748 (DOI)000237477400070 ()2-s2.0-33646710366 (Scopus ID)
Note
QC 20100906Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2017-12-14Bibliographically approved
3. AgTa0.5Nb0.5O3 thin film coplanar waveguide microwave capacitors
Open this publication in new window or tab >>AgTa0.5Nb0.5O3 thin film coplanar waveguide microwave capacitors
2005 (English)In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 77, 13-20 p.Article in journal (Refereed) Published
Abstract [en]

400 nm thick AgTa0.5Nb0.5O3 (ATN) films have been prepared by pulsed laser depositiontechnique on LaAlO3 (001) and sapphire (Al2O3-0112, r -cut) single crystal substrates.Comprehensive X-ray diffraction analysis showed epitaxial quality of ATN/LaAlO3films and preferentially (001) orientation of ATN/Al2O3 films. Voltage tunable microwavecapacitors were fabricated by lift-off technique on the surface of ferroelectricfilms. Microwave on-wafer tests were performed in the range from 1 to 40 GHz. Frequencydispersion is about 4.3%, voltage tunability is 4.7% @ 20 GHz and 200 kV/cm,loss tangent ∼0.068 @ 20 GHz, K-factor=tunability/tanδ is ranged from 124% @10 GHz to 35% @ 40 GHz.

Keyword
Coplanar waveguide, microwave on-wafer test, photolithography, pulsed laser deposition, scatering parameter measurements, ferroelectric thin films, silver tantalate niobates, voltage tunable device
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-6583 (URN)10.1080/10584580500413624 (DOI)000234386100003 ()2-s2.0-33645505627 (Scopus ID)
Note
QC 20100906Available from: 2006-12-12 Created: 2006-12-12 Last updated: 2017-12-14Bibliographically approved
4. Preparation of AgTaO3 and AgNbO3 thin films by pulsed laser deposition
Open this publication in new window or tab >>Preparation of AgTaO3 and AgNbO3 thin films by pulsed laser deposition
(English)Manuscript (preprint) (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-27144 (URN)
Note
QC 20101207Available from: 2010-12-07 Created: 2010-12-07 Last updated: 2010-12-07Bibliographically approved
5. Microwave Ba0.5Sr0.5TiO3 Thin Film Microwave Varactors
Open this publication in new window or tab >>Microwave Ba0.5Sr0.5TiO3 Thin Film Microwave Varactors
(English)Manuscript (preprint) (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-27145 (URN)
Note
QC 20101207 (Manuscript for the 13th International Congress on Thin Films, (ICTF 2005) Stockholm, Sweden) 2005.Available from: 2010-12-07 Created: 2010-12-07 Last updated: 2010-12-07Bibliographically approved
6. Microwave Properties of Niobate-Tantalate Film Coplanar WaveguideInterdigital Capacitors
Open this publication in new window or tab >>Microwave Properties of Niobate-Tantalate Film Coplanar WaveguideInterdigital Capacitors
(English)Manuscript (preprint) (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-27146 (URN)
Note
QC 20101207Available from: 2010-12-07 Created: 2010-12-07 Last updated: 2010-12-07Bibliographically approved

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