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1.
A wide range of Ca-doped (Ba0.7Sr0.3)TiO3 (BST) thin films (from 0 to 20 mol%) have been prepared on Pt/Ti/SiO2/Si (100) substrates by sol–gel technique. The structural and dielectric properties of BST thin films were investigated as a function of Ca dopant concentration. The results showed that the microstructure and dielectric properties of the BST films were strongly dependent on the Ca contents. With the Ca dopant concentration increasing, the grain size, dielectric constant and dielectric loss of the BST thin films decreased. As the content of Ca dopant reaches 10 mol%, the dielectric constant, dielectric loss, tunability, the value of FOM and the leakage current density are 281, 0.0136, 16.7%, 12.3 and 5.5?×?10?6 A/cm2, respectively. 相似文献
2.
Seon Young Cha Byung-Tak Jang Dong-Hwa Kwak Chang Ho Shin Hee Chul Lee 《Integrated ferroelectrics》2013,141(1-4):187-195
Abstract We propose Ir thin films as new electrode materials for high dielectric BST capacitors. Ir was found to be superior to Pt in a number of aspects such as resistivity, adhesion and surface roughness. The Pt/BST/Ir/SiO2/Si capacitors showed leakage currents as low as Pt/BST/Pt/SiO2/Si ones, but higher capacitance resulted. For endurance properties with +5V unipolar pulse trains, the dielectric constant of BST films on Ir decreased by only 10% below its initial value after switching of 109 cycles while that on Pt degraded by 30% after 108 cycles. Ir bottom electrode effects on BST film properties were well explained by the formation of IrO2 phases on the surface of Ir electrodes. 相似文献
3.
H. Basantakumar Sharma 《Integrated ferroelectrics》2015,159(1):14-22
Barium strontium titanate (Ba0.6Sr0.4TiO3) nanostructured thin films have been deposited on platinized silicon substrates by the sol-gel method. The as-fired films were found to be amorphous, which crystallize to cubic phase after annealing at 550°C in air for one hour. The low-frequency dielectric responses of the BST films were measured as functions of frequency range from 1 kHz to 1MHz. The thickness dependence dielectric constant of the BST thin films were measured in the temperature range from ?150°C to 150°C at 100 kHz and discussed in the light of an interfacial dead layer. All the samples showed a diffuse type phase transitions. Both the dielectric constant and loss tangent showed anomaly peaks at about 10°C, which corresponds to a tetragonal ferroelectric-to-cubic paraelectric phase transition. 相似文献
4.
ABSTRACT The (Ba0.5Sr0.5)TiO3 thin films were deposited onto LaNiO3 by RF-magnetron sputtering at 550°C. The influence of W content on microstructure and electrical properties of BST films were investigated. The surface and grain size become smoother and smaller as the W content increased. Besides, the dielectric constant, tunability, dissipation factor, and leakage current decreased when the W content increased. The 1% W is the optimal doping concentration. The resultant BST film, with proper dielectric constant and leakage current, has a tunability of 32%, a dissipation factor of 0.006, a FOM value of 53.3 under applied field of 450 kV/cm. 相似文献
5.
Eun-Suck Choi Woong-Chul Shin Tae-Seok Suh Sang-Shik Park Soon-Gil Yoon 《Integrated ferroelectrics》2013,141(1-4):297-304
Abstract The electrode structures of Pt/Ru and Ru on polycrystalline silicon (poly-Si) were prepared by metalorganic chemical vapor deposition (MOCVD) for high dielectric constant (Ba, Sr)TiO3(BST) capacitor integration. The electrode structures of Pt/Ru/poly-Si annealed above 700°C for 1h in oxygen atmosphere showed a smooth surface ·microstructure without any second phases on the platinum. The specific contact resistance of Pt/Ru and poly-Si in Pt/Ru/poly-Si structures annealed at 800°C was about 1.5 × 10?5 Ω-cm2. The step coverage of Ru film deposited at 150°C was 76% and those of Pt film deposited at 300°C on Ru (deposited at 150°C) was about 61.3%. 相似文献
6.
JUN-KI CHUNG SANG SU KIM DONG SIK BAE MYUNG-HO KIM TAE KWON SONG SEUNG EON MOON 《组合铁电体》2013,141(1):415-421
ABSTRACT Stress controlled epitaxial ferroelectric Ba0.5Sr0.5TiO3 (BST) films have been deposited on Gd2O3/SrTiO3 by pulsed laser deposition with oxygen background pressure of 200 mTorr at the deposition temperature of 750°C. In order to control the stress in BST films, oxygen pressures for Gd2O3 buffer layers have been varied from 0.1 to 100 mTorr, while that of BST films have been fixed at 200 mTorr. It has been found that the lattice parameters of the BST films deposited on Gd2O3 were changed. Furthermore, microwave properties of co-planar waveguide (CPW) fabricated on BST films were investigated by a HP 8510C vector network analyzer from 1–20 GHz. Large dielectric tunabilities were observed from the CPW's fabricated on BST films deposited on Gd2O3 layers deposited at low and high oxygen pressures, 0.1 and 100 mTorr, respectively. 相似文献
7.
Hyun Jin Chung Jin Hong Kim Won Seok Moon Seung Bin Park Cheol Seong Hwang Moon Yong Lee 《Integrated ferroelectrics》2013,141(2-4):185-197
Abstract A novel type of down-flow LSMCVD (Liquid Source Mist CVD) reactor was developed to prepare a high dielectric BST thin film on Pt electrode on Si wafer. Barium acetate [Ba (OOCCH3)2], strontium acetate [Sr (OOCCH3)2], and titanium isoproxide [Ti (OC3H7 i )4] were used as metal sources. Metal sources were dissolved in acetic acid, 1-butanol, or 2-methoxyethanol. BST [Ba/(Ba + Sr) = 0.7] film annealed on Pt/Ti/SiO2/Si above 650°C was polycrystalline. BST film has a (110) preferred orientation with increasing temperature. Surface roughness of BST film and grain size increased with increasing temperature. The metal-oxygen bond was formed at 650°C as shown in the spectra of FTIR. The depth profiles of elements of BST thin films indicated a uniform composition throughout the film. BST films annealed at 750°C showed a dielectric constant and a tanδ of 390 (thickness: 150 nm) and 0.06 at a frequency of 100 kHz, respectively. The behavior of capacitance of the BST film with bias voltage showed paraelectric property. BST film annealed at 750°C had the leakage current density of 3.2 (μA/cm2) at a bias voltage of 2V. 相似文献
8.
CH. G. WU W. L. ZHANG Y. R. LI X. ZH. LIU J. ZHU B. W. TAO 《Integrated ferroelectrics》2013,141(1):26-34
ABSTRACT The integrated single element infrared detectors were developed for high-loading smart munition application using (Ba0.65Sr0.35)TiO3 (BST) pyroelectric films and SiO2 thermal insulating layer. (Ba,Sr)RuO3 (BSR) seeding-layer was deposited on the Pt/Ti/SiO2/Si to induce BST films c-axis preferred orientation growth. The capacitance dependant with temperature of BST films were measured at the temperature ranging from 230 K to 340 K, releasing that the temperature coefficient of capacitance was 1.6%/K. The pyroelectric coefficient of BST films was 7.45 × 10? 7 C/K cm2 measured by dynamic method. Infrared response evaluation of the fabricated sensor has been carried out with D* of 6.34 × 107 cm Hz1/2/W indicating that the integrated infrared detectors have potential application as gun-launched smart munition seeker. 相似文献
9.
F. W. Van Keuls C. H. Mueller R. R. Romanofsky J. D. Warner F. A. Miranda H. Jiang 《Integrated ferroelectrics》2013,141(1-4):437-448
Abstract Historically, tunable dielectric devices using thin crystalline BaxSr1-x TiO3 (BST) films deposited on lattice-matched substrates, such as LaAlO3, have generally been grown using pulsed laser deposition (PLD). Highly oriented BST films can be grown by PLD but large projects are hampered by constraints of deposition area, deposition time and expense. The Metal-Organic Chemical Liquid Deposition (MOCLD) process allows for larger areas, faster turnover and lower cost. Several BST films deposited on LaAlO3 by MOCLD have been tested in 16 GHz coupled microstrip phase shifters. They can be compared with many PLD BST films tested in the same circuit design. The MOCLD phase shifter performance of 293° phase shift with 53 V/μm dc bias and a figure of merit of 47°/dB is comparable to the most highly oriented PLD BST films. The PLD BST films used here have measured XRD full-width-at-half-maxima (FWHM) as low as 0.047°. The best FWHM of these MOCLD BST films has been measured to be 0.058°. 相似文献
10.
Thickness dependent ferroelectric properties of BSTO thin films deposited by RF magnetron sputtering
Jong-Yoon Ha Ji-Won Choi Chong-Yun Kang S. F. Karmanenko Doo Jin Choi Seok-Jin Yoon Hyun-Jai Kim 《Journal of Electroceramics》2006,17(2-4):141-144
The thickness dependence of ferroelectric permittivity of (Ba, Sr)TiO3 has been investigated. The BST films could be obtained to have a simple cubic perovskite structure, space group Pm3m, and
practically c-axis epitaxial structure deposited at 800∘C. Through post-annealing process, we have improved the dielectric properties; dielectric permittivity, dielectric loss, and
tunability. The change in dielectric properties before and after annealing is attributed to the change in film strain and
the contraction in film lattice. As the thickness of BST films increases from 55 nm to 350 nm, the dielectric constant of
BST films increases from about 100 to above 670 due to the reduction of interfacial dead layers with low dielectric constant
between films and top electrodes. The dielectric loss of BST thin films decreased as the thickness increases. The existence
of interfacial dead layers in a thinner film had a larger effect on the effective dielectric constant than tensile strain
between the BST films and MgO substrate. 相似文献
11.
Mi-Hwa Lim Hyun-Suk Kim Nan-Young Kim Ho-Gi Kim Il-Doo Kim Seung Eon Moon Min-Hwan Kwak Han-Cheol Ryu Su-Jae Lee 《Journal of Electroceramics》2004,13(1-3):239-243
Highly (100) preferred undoped and 1–5% Ni-doped Ba1–xSrxTiO3 (BST) thin films were deposited onto MgO (100) single crystal substrate at 750°C using pulsed laser deposition. BST thin film-based interdigital capacitors (IDC) were prepared by standard photolithography process. The microwave properties of BST films were measured at 10 GHz. Ni-doped BST films showed better dielectric properties by exhibiting improved dielectric Q while retaining an appropriate capacitance tuning compared to undoped BST films. 1% Ni-doped BST film showed the maximum figure of merit of 2896.1. It is suggested that 1 mol% Ni doped BST film is an effective candidate for high performance tunable device applications. 相似文献
12.
ABSTRACT The (PbxSr1-x)TiO3 (PST) thin films were deposited on LaNiO3 (LNO(1 0 0))/ Pt/Ti/SiO2/Si substrates electrode by RF-magnetron sputtering using three different Pb target composition ranging from 32.5%~37.5% and different process condition. Structural and dielectric properties of the PST thin films for tunable microwave and DRAM application were investigated. The PST thin films deposited at 400°C show higher dielectric constant than those post-annealed at 600°C because of better crystallization. The former also have lower leakage current around 10?8 A/cm2 up to applied field of 350 kv/cm, which is suitable for DRAM application. On the other hand, the post-annealed PST thin films have satisfactory tunability around 58% and figure of merit around 30, which are more suitable for microwave device application. 相似文献
13.
ABSTRACTThe influences of Y and Mn alternately doped order on the microstructures and dielectric properties of the Ba0.6Sr0.4TiO3 (BST) films were reported in this paper. The Y and Mn alternately doped BST films were designed as YBST/MnBST/… and MnBST/YBST…multilayer films orderly expressed as (Y/Mn)M and (Mn/Y)M for short, and prepared on Pt/Ti/SiO2/Si wafers by an improved sol-gel method, where Y and Mn represent yttrium doped BST layer and manganese doped BST layer, and M is cycle unit, respectively. The microstructures of the alternately doped BST films were observed by SEM and the capacitance-voltage curves at 100 kHz or 1 MHz were measured by a HP4284A LCR meter and the dielectric properties in the range of 1GHz were measured by an E4991A impedance analyzer. Compared to Y or Mn doped multilayer BST film, (Y/Mn)M and (Mn/Y)M show higher dielectric tunability and lower dielectric loss with higher dielectric constant. Moreover, (Y/Mn)M show better dielectric properties than (Mn/Y)M because (Y/Mn)M show granular microstructures independent of M, while the (Mn/Y)M show granular microstructures when M is 2 and add to a surface layer of columnar microstructures on the granular microstructures when M is 4. The related mechanisms were obtained in terms of the XRD phase structures, the cross-sectional SEM microstructures and the AFM morphologies. 相似文献
14.
The Effect of Stress on the Microwave Dielectric Properties of Ba0.5Sr0.5TiO3 Thin Films 总被引:1,自引:0,他引:1
James S. Horwitz Wontae Chang Wonjeong Kim Syed B. Qadri Jeffrey M. Pond Steven W. Kirchoefer Douglas B. Chrisey 《Journal of Electroceramics》2000,4(2-3):357-363
Single phase, (1 0 0) epitaxial Ba0.5Sr0.5TiO3 (BST) films have been deposited onto (1 0 0) LaAlO3 and MgO substrates by pulsed laser deposition (PLD). The capacitance and dielectric losses of as-deposited and annealed films have been measured from 1–20 GHz as a function of electric field (0–80 kV/cm) at room temperature. The dielectric properties are strongly affected by the substrate type, post-deposition annealing time (6 h) and temperature (1200°C). For epitaxial BST films deposited onto MgO, it is observed that, after a post-deposition anneal the dielectric constant and the dielectric loss decreases. For epitaxial BST films deposited onto LAO, a post-deposition anneal (1000°C) results in an increase in the dielectric constant and an increase in the dielectric loss. The dc electric field induced change in the dielectric constant tends to increase with the dielectric constant and is largest for as-deposited films on MgO and post-deposited annealed films on LAO. In general, for epitaxial BST films, a large electric field effect is observed in films that have a large dielectric loss and a small electric field effect in films that have a low dielectric loss. High resolution X-ray diffraction measurements indicate that deposited film exhibit a significant tetragonal distortion which is strongly affected by a by a post deposition anneal. The observed differences in dielectric properties of the epitaxial BST films on MgO and LAO are attributed to the differences in film stress which arise as a consequence of the lattice mismatch between the film and the substrate and the differences in the thermal coefficient of expansion between the film and the substrate. A thin amorphous buffer layer of BST has been used to relieve stress induced by the lattice mismatch between the film and the substrate. Unlike epitaxial films, stress relieved films do not show an inverse relationship between dielectric tuning and Q (1/tan) and may be superior materials for tunable microwave devices. 相似文献
15.
《Integrated ferroelectrics》2013,141(1):1305-1314
Compositionally graded (Bax,Sr1 ? x)TiO3 [BST] ferroelectric thin films have been received much attention in graded ferroelectric devices due to their unique properties, such as large pyroelectric coefficients, large polarization offset and small temperature coefficient of dielectric constant for microwave tunable devices. Compositionally graded BST thin films were deposited epitaxially on LaAlO3 [LAO] and Nb-doped SrTiO3 [STO:Nb] substrates by pulsed laser deposition. The planar and parallel dielectric properties of compositionally graded BST epitaxial thin films ware investigated in the frequency ranges of 100 Hz ~ 1 MHz as a function of the direction of the composition gradient with respect to the substrate at room temperature. The dielectric properties of the graded BST films depended strongly on the direction of the composition gradient with respect to the substrate. The graded ST → BT films grown on LAO and STO:Nb substrates exhibited a excellent dielectric properties than the graded BT → ST films. 相似文献
16.
ABSTRACT BaTiO3 films were deposited by the direct vapor deposition (DVD) technique to prepare thin dielectric layers for multilayer ceramic chip capacitors (MLCCs). The BaTiO3 films were successfully prepared by co-evaporation of the BaTiO3 ceramic and Ti metal source. The films deposited at room temperature and 600°C were amorphous and crystalline phases, respectively. The intensity of (110) and (111) peaks increased as Ba/Ti ratios were close to stoichiometric composition. BaTiO3 films deposited with e-beam power of 700 W showed the deposition rate of 33 nm/min. The dielectric constant and dissipation factor of BaTiO3 films measured at 1 kHz were 150~ 180 and 2~ 5%, respectively. The capacitance decreased with increasing the temperature and varied only between 787pF and 752pF in the temperature range 15~ 125°C. 相似文献
17.
Abstract Excellent single crystal BaxSr1-xTiO3 (BST) films were grown on LaAlO3 substrates using the metal-organic chemical liquid deposition (MOCLD) method. Very low losses (tanδ ∽0.002-0.008) were measured from these films at 400 KHz. Biaxially oriented BST films were successfully grown on polycrystalline YIG substrates using both MOCLD and pulsed laser deposition methods with biaxially oriented MgO and YSZ buffer layers. The dielectric losses of the films range from 0.005 to 0.015 while 25% of dielectric constant change was observed with 40V bias voltage up to 10 MHz. Both the dissipation and dielectric constant of the films remained nearly constants over a wide temperature range (77 K to 380 K). A dual-tuning microwave coplanar phase shifter using a BST film grown on a MgO buffered polycrystalline YIG substrate was fabricated. A significant phase shift was observed in GHz frequency range when an electric bias or a magnetic field was applied to the device. 相似文献
18.
Rajesh B. Khamankar Jiyoung Kim C. Sudhama Jack C. Lee 《Integrated ferroelectrics》2013,141(3):169-176
Abstract The effects of deposition temperature on the properties of thin films of sputtered lead-zirconate-titanate (PZT) have been studied for ULSI DRAM storage capacitor dielectric applications. The films were deposited by reactive dc magnetron sputtering from a multi-component target. The grain size for the films deposited at 400°C was found to be less than 1000 Å, while it was ~ 10–30 μm for films deposited at 200°C. Small grain-sized material is desirable since it leads to better cell-to-cell uniformity in terms of charge storage capacity and other electrical and reliability properties. The optimum lead compensation was found to increase as the deposition temperature (T dep) increased. Leakage current density stays fairly constant as T dep is varied. As-deposited films, with a deposition temperature of 500°C, were rich in the perovskite phase and showed a high charge storage density of 11.2 μC/cm2 and a low leakage current density of 5.1 × 10?7 A/cm2 (both at 1.5 V). This implies the possibility of eliminating the high temperature crystallization-annealing step. 相似文献
19.
D. Y. Wang Y. Wang K. H. Wong K. P. Lor H. P. Chan K. S. Chiang 《Integrated ferroelectrics》2013,141(1):443-451
ABSTRACTBarium strontium titanate [Ba0.6Sr0.4TiO3 or BST (60/40)] thin films were deposited on MgO (100) substrates using pulsed laser deposition. X-ray diffraction (XRD) measurements revealed that the BST thin films had epitaxially grown on the MgO (100) substrates. The surface morphology of the thin films was observed using an atomic force microscope and the grain size was found to be about 100–150 nm. The surface roughness was around 4.9 nm for a 250 nm thick film. The optical transmittance of the BST thin film was measured using a transmission mode ellipsometer. The BST/MgO configuration was highly transparent in the visible region. The optical band gap energy of the BST film, calculated by applying the Tauc relation, was 3.56 eV. Optical waveguide characteristics of the BST (60/40) thin film were determined using a prism coupler. The electro-optic (E-O) properties were measured at 632.8 nm wavelength using a phase modulation detection method. The BST film exhibited a predominately quadratic E-O behavior and the quadratic E-O coefficient was found to be 0.58 × 10? 17 m2/V2. 相似文献
20.
Abstract Bi2(Zn1/3Nb2/3)2O7, BiZN, materials possess high dielectric constant and low loss factor in microwave frequency region. They have good potential for device application, especially in the form of thin films. However, the microwave dielectric properties of a thin film are very difficult to be accurately measured. Evaluation on the dielectric behavior of the films through the performance of the microstrip line devices made of these films involves metallic conduction and stray field losses. A novel measuring technique, which can directly evaluate the microwave dielectric properties of a thin film is thus urgently needed. In this paper, BiZN thin films were grown on [100] MgO single crystal substrates using pulsed laser deposition process. The high-frequency dielectric properties of thus obtained thin films were determined using optical transmission spectroscopy (OTS). The [100] preferentially oriented films with pyrochlore structure can be obtained for the thin films deposited at 400–600°C substrate temperature under 0.1 mbar oxygen pressure. OTS measurements reveal that the index of refraction (n=1.95–2.35) and absorption coefficient (k=0.28x10?4-2.25 × 10?4 nm?1) of the films vary insignificantly with the crystallinity of the BiZN films. 相似文献