Thin Na0.5K0.5NbO3 Films for Varactor Applications

2000 ◽  
Vol 623 ◽  
Author(s):  
C.-R. Cho ◽  
J.-H. Koh ◽  
A. Grishin ◽  
S. Abadei ◽  
P. Petrov ◽  
...  
Keyword(s):  
Microwave Frequency ◽  
Dissipation Factor ◽  
Leakage Currents ◽  
Low Frequencies ◽  
Si Substrates ◽  
Low Dielectric ◽  
Low Leakage ◽  
Tunable Microwave Device ◽  
Device Applications ◽  
Spectroscopy Studies

AbstractSingle phase Na0.5K0.5NbO3 (NKN) thin films have been pulsed laser deposited on SiO2/Si(C-01) wafers and LaAlO3(001) and MgO(001) single crystals. Radio frequency (up to 1 MHz) and microwave (up to 50 GHz) dielectric spectroscopy studies have been carried out to characterize thin NKN films for electrically tunable microwave device applications. Films on single crystal oxide substrates showed tunabilities as high as 30-40 % at 40 V bias and dissipation factor of 0.01-0.02 at 1 MHz. The films on Si substrates showed low dielectric losses of < 0.01, and low leakage currents. Dielectric properties of ferroelectric films on Si substrates at low frequencies are greatly influenced by the depletion capacitance and the resistance inserted by semiconductor substrate. Microwave frequency measurements for NKN film on Si wafers yield more than 10 % tunability at 50 GHz and loss tan σ <0.1 at 10 GHz.

Ferroelectric Na0.5K0.5NbO3 Films for Voltage Tunable Microwave Devices

2000 ◽  
Vol 656 ◽  
Author(s):  
Choong-Rae Cho ◽  
Alex Grishin ◽  
Johanna Andrèasson ◽  
Ture Lindbäck ◽  
Saeed Abadei ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Phase ◽  
Microwave Frequency ◽  
Dissipation Factor ◽  
Si Substrate ◽  
Applied Bias ◽  
Tunable Microwave Device ◽  
Oxide Substrates ◽  
Tunable Microwave ◽  
Device Applications

ABSTRACTSingle phase Na0.5K0.5NbO3 (NKN) thin films have been pulsed laser deposited on Al2O3(0112), LaAlO3(001), and MgO(001) single crystal substrates as well as on the SiO2/Si(001) wafers to demonstrate films feasibility for voltage tunable microwave device applications. NKN film texture has been found to be quite different on three different single crystals: highly c-axis oriented on Al2O3, “cube-on-cube” epitaxial quality on LaAlO3, bi-axial textures on MgO, while NKN films grown on Si substrate with various thickness of SiO2 buffer layer possess highly c-axis oriented quadrupled structure. NKN film interdigital capacitors fabricated onto single crystal oxide substrates showed tunability of 30-40 % and dissipation factor of 0.01-0.02 at 1 MHz and applied electric field of 100kV/cm. Microwave frequency measurements for NKN/Si varactors yield 13 % tunability and dielectric loss tanδ as low as 0.012 at 40 GHz under 200 kV/cm applied bias.

Niobate Films for Microwave Applications

2001 ◽  
Vol 666 ◽  
Author(s):  
C.-R. Cho ◽  
J.-H. Koh ◽  
A.M. Grishin ◽  
S. Abadei ◽  
S. Gevorgian
Keyword(s):  
Dielectric Loss ◽  
Dielectric Permittivity ◽  
Pulsed Laser ◽  
Microwave Spectroscopy ◽  
Growth Mechanisms ◽  
Si Substrates ◽  
Device Applications ◽  
Microwave Applications ◽  
Maximum Electric Field ◽  
Spectroscopy Studies

ABSTRACTSubmicron thick niobate films, Na0.5K0.5NbO3 (NKN) and Ag0.9Ta0.42Nb0.58O3-δ (ATN), have been pulsed laser deposited on MgO, Pt80Ir20, and Si substrates for microwave device applications. Strong bi-axial (001)-(011) texture observed in both films on MgO substrates indicates that there are major similarities in the growth mechanisms in these films. The dielectric permittivity ε′ of NKN film increases monotonously with temperature, while that of ATN shows a weak temperature dependence (about 21% of variation) in a wide temperature range from 77 K to 400 K. Measured tunability Δε′/ε′ and dielectric loss tanδ for niobate/MgO interdigital capacitors have been found to be (Δε′/ε′)NKN = 40%, tanδNKN = 1.4-2.3% and (Δε′/ε′)ATN = 4.3%, tanδATN = 0.23-0.25% at 1 MHz under maximum electric field of 100 kV/cm. Microwave spectroscopy studies for NKN/Si varactors show (Δε′/ε′)NKN/Si of 13% and tanδNKN/Si = 1.2-6.6% at 40 GHz @ 200 kV/cm.

Silicon-On-Insulator Mosfets Fabricated in Zone-Melting-Recrystallized Poly-Si Films on SiO2

1981 ◽  
Vol 4 ◽  
Author(s):  
B­Y. Tsaur ◽  
M. W. Gels ◽  
John C. C. Fan ◽  
D. J. Silversmith ◽  
R. W. Mountain
Keyword(s):  
Carrier Mobility ◽  
High Surface ◽  
Zone Melting ◽  
Silicon On Insulator ◽  
Surface Electron ◽  
Leakage Currents ◽  
Si Substrates ◽  
Enhancement Mode ◽  
Low Leakage ◽  
Si Films

ABSTRACTN- and p-channel enhancement-mode MOSFETs have been fabricated in Si films prepared by zone-melting recrystallization of poly-Si deposited on SiO2-coated Si substrates. The transistors exhibit high surface mobilities, in the range of 560–620 cm2/V−s for electrons and 200–240 cm2/V−s for holes, and low leakage currents of the order of 0.1 pA/μm (channel width). Uniform device performance with a yield exceeding 90% has been measured in tests of more than 100 devices. The interface between the Si film and the SiO2 layer on the substrate is characterized by an oxide charge density of 1–2 × 1011 cm−2 and a high surface carrier mobility. N-channel MOSFETs fabricated inSi films recrystallized on SiO2-coated fused quartz subtrates exhibit surface electron mobilities substantially higher than those of single-crystal Si devices because the films are under a large tensile stress.

MOCVD of SrTa2O6 Thin Films for High-k Applications

2004 ◽  
Vol 811 ◽  
Author(s):  
Stephan Regnery ◽  
Reji Thomas ◽  
Hans Haselier ◽  
Peter Ehrhart ◽  
Rainer Waser ◽  
...  
Keyword(s):  
Thin Films ◽  
Process Window ◽  
Leakage Currents ◽  
Si Substrates ◽  
Mocvd Reactor ◽  
Low Leakage ◽  
High K ◽  
Single Source Precursor ◽  
Mis Capacitors ◽  
Low Pressures

ABSTRACTSrTa2O6 thin films with thickness between 6 and 150nm were deposited in a multi-wafer planetary MOCVD reactor combined with a TRIJET® liquid delivery system using a single source precursor, strontium-tantalum-(methoxyethoxy)-ethoxide dissolved in toluene. A rather narrow process window for the deposition of stoichiometric SrTa2O6 was found for this precursor at low pressures and a susceptor temperature around 500°C. Films were grown on Pt/TiO2/SiO2/Si, TiNx/Si, and SiO2/Si substrates. The as-deposited films were X-ray amorphous and could be crystallized by post-annealing at a temperature ≥700°C. The SrTa2O6 phase was dominating within a broad range of compositions (Sr/Ta: 0.4–0.7) and a perovskite type phase was observed for Sr/Ta > 0.7. The electrical properties have been investigated with MIM and MIS capacitors after sputter deposition of Pt top electrodes. The amorphous films had a relative permittivity, ε, in the range of 25–45, and low leakage currents. Crystallized films were investigated with Pt MIM capacitors. For stoichiometric SrTa2O6 the dielectric permittivity reached values of ε = 100–110, but the leakage currents were increased. Remarkably, the permittivity is not very sensitive to deviations from the exact stoichiometry of the SrTa2O6 phase (Sr/Ta: 0.40.7), but a decrease to values of ε = 30–40 is observed along with the phase transition at high Sr contents.

Deposition and Characterization of Pyroelectric PMN-PT Thin Films for Uncooled Infrared Focal Plane Arrays

2011 ◽  
Vol 687 ◽  
pp. 242-246
Author(s):  
Yan Xue Tang ◽  
Yue Tian ◽  
Fei Fei Wang ◽  
Wang Zhou Shi
Keyword(s):  
Thin Films ◽  
Focal Plane ◽  
High Performance ◽  
Pyroelectric Coefficient ◽  
Focal Plane Arrays ◽  
Infrared Focal Plane Arrays ◽  
Si Substrates ◽  
Low Dielectric ◽  
Device Applications ◽  
Electric Filed

Modern uncooled infrared focal plane arrays (UFPA) development is oriented toward silicon microstructure monolithic arrays by employing pyroelectric thin films with continuing trends in high performance and miniaturization. In order to exploit high performance pyroelectric thin films, (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3(PMN-PT) thin films withx= 0.26 were deposited on LaNiO3/Si substrates by the radio-frequency magnetron sputtering technique. (110) preferred orientation thin films with pure perovskite structures were obtained at a substrate temperature of 500°C. The ferroelectric, dielectric and pyroelectric properties of the films were investigated. The films show a typical polarization – electric filed hysteresis loop with a large remnant polarization of 17.2 μC/cm2. At room temperature, the high pyroelectric coefficient of 3.1 × 10-4C/m2K together with low dielectric constant of 470 and loss tangent of 0.04 render the film promising for uncooled infrared device applications. The origin of the differences in electrical properties between the films and bulk materials has also been discussed.

MFMOS Capacitor with Pb5Ge3O11 Thin Film for One Transistor Ferroelectric Memory Applications

1999 ◽  
Vol 596 ◽  
Author(s):  
T. K. Li ◽  
S. T. Hsu ◽  
J. J. Lee ◽  
Y. F. Gao ◽  
M. Engelhard
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Ferroelectric Properties ◽  
Memory Window ◽  
Low Dielectric Constant ◽  
Ferroelectric Capacitor ◽  
Si Substrates ◽  
Low Dielectric ◽  
Low Leakage ◽  
Ferroelectric Hysteresis

AbstractA ferroelectric Pb5Ge3O11 thin film with a low dielectric constant is proposed for application in one transistor ferroelectric memories. A strong depolarization voltage on the ferroelectric capacitor with MIFSFET structures diminishes the remanent polarization significantly and, therefore, the low dielectric constant becomes very important to widen the memory window. A memory window of 3V was estimated for the MFMOS memory structure with 2000Å ferroelectric Pb5Ge3O11 and a 100Å gate oxide. In the second part of this paper, Pb5Ge3O11 films deposited on Ir/Ti/SiO2/Si substrates, by using MOCVD system, was demonstrated. Germanium ethoxide, Ge(OC2H5)4, and lead bis-tetramethylheptadione, Pb(thd)2, were used as the MOCVD precursors. The film composition, phase formation, microstructure and ferroelectric properties are reported. The c-axis oriented Pb5Ge3O11 thin films prepared by MOCVD and RTP post-annealing showed a square ferroelectric hysteresis loop with Pr of 2.83 μC/cm2 and EC of 49 kV/cm. A low leakage current of 7.5 × 10−7 A/cm2 at 100 kV/cm and low dielectric constant of 41 were also demonstrated.

Fabrication and Electrical Characterization of Ba(1-x)SrxTiO3 Based Thin Films

2003 ◽  
Vol 784 ◽  
Author(s):  
E. Ngo ◽  
W. D. Nothwang ◽  
C. Hubbard ◽  
M. W. Cole ◽  
W. Chang ◽  
...  
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Low Frequency ◽  
Pulsed Laser ◽  
Electrical Characterization ◽  
Microwave Frequency ◽  
Thin Film Deposition ◽  
Dissipation Factor ◽  
Film Deposition ◽  
Device Applications

ABSTRACTOver the past several years there has been a tremendous growth and development of thin film deposition technology in the electronics industry. Ferroelectric thin films have been recognized for their unique dielectric properties and appear to be desirable for tunable microwave device applications. Among the most promising candidates for such applications are Ba(1−x)SrxTiO3[BST] and BST-based thin films. In this work pure BST and acceptor doped BST-based thin films were fabricated on (100) MgO substrates via pulsed laser deposition [PLD]. X-ray diffraction (XRD) in conjunction with the atomic force microscope (AFM) were used to analyze the film crystalinity and surface morphology. The dielectric properties were characterized at both 100 kHz and 20 GHz. The MIM capacitor configuration was used to attain the dielectric properties at 100 kHz and the microwave measurements, S11 reflection parameters, were achieved via interdigitated capacitor design with Au/Ag top electrodes. The parallel resistor-capacitor models were used to determine the microwave capacitance and Q factors and the permittivity was calculated using a modified conformal-mapping partial-capacitance method using the dimension of the capacitors. Our results demonstrated that the low frequency and microwave frequency dielectric properties were strongly influenced by the film composition. Specifically, the Mg doping served to lower the dissipation factor, permittivity, and tunability of the BST based films at both frequencies. This work demonstrates that the BST based thin films possessed excellent microstructural, structural, and dielectric properties. The structure-process-property correlations of the pulsed laser deposited BST and acceptor doped BST-based thin films are discussed in detail.

Effects of Excess Pb on Crystallization and Electrical Properties of Ferroelectric PZT Films Deposited by Reactive RF Magnetron Sputtering

1994 ◽  
Vol 361 ◽  
Author(s):  
S.D. Bernstein ◽  
T.Y. Wong ◽  
S.R. Collins ◽  
Yanina Kisler ◽  
R.W. Tustison
Keyword(s):  
Electrical Properties ◽  
Perovskite Phase ◽  
Ion Beam ◽  
Ferroelectric Properties ◽  
Rf Magnetron Sputtering ◽  
Ion Beam Sputtering ◽  
Leakage Currents ◽  
Si Substrates ◽  
Low Leakage ◽  
Beam Sputtering

ABSTRACTFilms were deposited onto unheated, Ti/Pt coated Si substrates by reactive sputtering in an argon-oxygen atmosphere from a sintered PZT target, and subsequently crystallized at temperatures between 550 and 650 °C. Pt/PZT/Pt capacitors were formed by ion beam sputtering of top electrodes through a shadow mask. Electrical properties were found to depend on gas pressure during deposition. This effect is interpreted in terms of variations in film stoichiometry (particularly Pb content). Films with large excesses of Pb were found to exhibit high leakage currents and poor ferroelectric behavior, whereas films with lower excesses of Pb had low leakage currents, and good ferroelectric properties. Films with the largest Pb excess had a random orientation, while the film with the lowest Pb excess had a preferred (111) orientation. With 550 °C crystallization temperatures the films consist of a mixture of ferroelectric perovskite phase and either PZT pyrochlore or PbO. At higher crystallization temperatures no pyrochlore is detected.

Effects of Rare Earth Incorporation on the Ferroelectric and Dielectric Properties of Sol-Gel Derived PbTiO3 Films

1994 ◽  
Vol 346 ◽  
Author(s):  
G. Teowee ◽  
C.D. Baertlein ◽  
S.A. Schlegel ◽  
J.M. Boulton ◽  
D.R. Uhlmann
Keyword(s):  
Dielectric Constant ◽  
Rare Earth ◽  
Remanent Polarization ◽  
Sol Gel ◽  
Dissipation Factor ◽  
Leakage Currents ◽  
Dielectric Characterization ◽  
Low Leakage ◽  
Pzt Films ◽  
Rare Earth Doped

ABSTRACTFerroelectric (FE) films, especially PZT films, have received increasing attention for microelectronics applications such as FE memory and in high density DRAM's. While rare earth doped PbTiO3 ceramics has been studied for SAW and piezoelectric applications, rare earth-doped films seldom have been systematically explored. A series of sol-gel derived PbTiO3 films with varying amounts (5-15 mole %) of rare earths (such as, Nd, Sm, Tb, Dy, Er ,Yb and La ) have been prepared using acetates and alkoxides as precursors. The solutions were spin coated onto platinized Si wafers. The effects of the type and amount of rare incorporation on the phase assembly and microstructure have been quantified. The results of dielectric characterization (e.g., dielectric constant, dissipation factor and leakage currents) and FE behaviors (viz remanent polarization, and coercive field) are presented; these films exhibited low leakage currents (3E-10 A/cm2) and much higher dielectric constant (up to 525) compared to undoped PbTiO3 films.

Defects in β-SiC thin films grown on α-SiC substrates

1988 ◽  
Vol 46 ◽  
pp. 568-569
Author(s):  
Karren L. More
Keyword(s):  
Thin Films ◽  
Semiconductor Device ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Substrate Material ◽  
Growth Interface ◽  
Si Substrates ◽  
Thermal Expansion Coefficients ◽  
Device Applications ◽  
Expansion Coefficients

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.

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