共查询到20条相似文献,搜索用时 15 毫秒
1.
采用脉冲激光沉积(PLD)法在Pt/Ti/SiO2/Si(001)基片上制备了Ba0.6Sr0.4TiO3(BST)薄膜,对Pt/BST/Pt电容器在空气中进行400℃快速退火(RTA)处理,研究了快速退火对Pt/BST/Pt电容器的结构和性能的影响。结果表明:快速退火虽然对BST薄膜的结晶质量影响较小,但却极大改善了Pt/BST/Pt电容器的电学性能。当测试频率为100kHz、直流偏压为0V时,介电损耗从快速退火前的0.07减小到0.03,介电常数和调谐率略有增加。快速退火后负向漏电流过大现象得到了明显抑制,正负向漏电流趋于对称,在300×103V/cm电场强度下,漏电流密度为4.83×10–5A/cm2。 相似文献
2.
We have been developing a monolithic microbolometer technology for uncooled infrared focal plane arrays (Uncooled IRFPAs) along the route from fabricating pixels of thin-film dielectric bolometers on micromachined silicon substrates. In the paper, the thermal-sensitive barium strontium titanate (BST) thin film capacitors for that objective prepared by Radio-Frequency Magnetron sputtering have been investigated focusing on the condition of fabrication of BST thin films. Capacitor-Temperature properties of the thermal-sensitive BST thin film capacitors have been measured with impedance analyzer. According to the Capacitor-temperature curves, these indicated that the temperature coefficient of dielectric constant (TCD) within the ambient temperature region highly depended on the Radio-Frequency Magnetron sputtering condition of fabrication of BST thin films. BST thin film capacitors with TCD-value more than 21%/K have been prepared on the optimized condition. That is a good base for preparation of dielectric bolometer mode of uncooled IRFPAs. 相似文献
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Thermo-Sensitive Ba0.64Sr0.36TiO3 Thin Film Capacitors for Dielectric Type Uncooled Infrared Sensors
Liang Dong Ruifeng Yue Litian Liu Xiaoning Wang Jianshe Liu Tianling Ren 《Journal of Infrared, Millimeter and Terahertz Waves》2003,24(8):1341-1349
Ba0.64Sr0.36TiO3 (BST) thin films are prepared on Pt/Ti/SiO2/Si3N4/SiO2/Si substrates by a sol-gel method. Thermo-sensitive BST thin film capacitors with a Metal-Ferroelectrics-Metal (M-F(BST)-M) structure are fabricated as the active elements of dielectric type uncooled infrared sensors. XRD are employed to analyze the crystallographic structures of the films. AFM observations reveal a smooth and dense surface of the films with an average grain size of about 35 nm. Rapid temperature annealing (RTA) process is a very efficient way to improve crystallization quality. The preferable annealing temperature is 800°C for 1 min. The butterfly shaped C-V curves of the capacitors indicate the films have a ferroelectric nature. The dielectric constant and dielectric loss of the films at 100 kHz are 450 and 0.038, respectively. At 25°C, where the thermo-sensitive capacitors work, the temperature coefficient of dielectric constant (TCD) is about 5.9 %/°C. These results indicate that the capacitors with sol-gel derived BST thin films are promising to develop dielectric type uncooled infrared sensors. 相似文献
5.
Al Ahmad M. Brunet M. Payan S. Michau D. Maglione M. Plana R. 《Microwave and Wireless Components Letters, IEEE》2007,17(11):769-771
This letter reports low-field wide-tunable interdigitated barium strontium titanate (BST) capacitors. The capacitors consisting of BST thin film dielectric, silicon substrate, and gold metallization have been fabricated. The capacitance exhibits 0.2 pF at zero-bias and shows a tunability of 63% with an applied electric field of 1.4 V/mum. This corresponds to a 3.5 mum electrode gap width and a 5 V dc bias. Microwave measurements reveal a zero bias film quality of 50 around 30 GHz. 相似文献
6.
Tung-Sheng Chen Balu V. Katakam S. Jian-Hung Lee Lee J.C. 《Electron Devices, IEEE Transactions on》1999,46(12):2304-2310
Excellent electrical characteristics of RF-sputtered Barium Strontium Titanate (BST) thin-film capacitors with iridium (Ir) electrodes were obtained and the influence of Ir on device properties was investigated. In contrast to conventional Pt-electroded system, BST capacitors with Ir electrodes exhibit higher polarization and slightly higher leakage current. The stronger crystallinity of a thin BST layer (~70 Å) initially grown on Ir substrate is believed to be the cause for higher charge storage density of the Ir-electroded capacitors. However, this higher polarization is accompanied by higher dielectric dispersion (3.12% per decade for Ir versus 1.98% for Pt electrodes). On the other hand, leakage current appears to be dominated by the Schottky barrier formed by Ir-BST and Pt-BST contacts, respectively, at high field. The analysis from temperature-dependent J-V data indicates a lower barrier height for the Ir-BST contact than Pt-BST contact. The slightly higher leakage current density of the BST capacitors with Ir electrodes can thus be attributed to the lower barrier height 相似文献
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Acikel B. Taylor T.R. Hansen P.J. Speck J.S. York R.A. 《Microwave and Wireless Components Letters, IEEE》2002,12(7):237-239
In this paper, a new device topology has been proposed to implement parallel plate capacitors using BaxSr1-xTiO3 (BST) thin films. The device layout utilizes a single parallel capacitor and minimizes conductor losses in the base electrode. The new design simplifies the monolithic process and overcomes the problems associated with electrode patterning. An X-band 180° phase shifter has been implemented using the new device design. The circuit provided 240° phase shift with an insertion loss of only 3 dB at 10 GHz at room temperature. We have shown a figure of merit 93°/dB at 6.3 GHz and 87°/dB at 8.5 GHz. To our knowledge, these are the best figure of merit results reported in the literature for distributed phase shifters implemented using BST films at room temperature 相似文献
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Huey-Daw Wu Zhihang Zhang Barnes F. Jackson C.M. Kain A. Cuchiaro J.D. 《Applied Superconductivity, IEEE Transactions on》1994,4(3):156-160
In this paper we report the construction of both slot capacitors on bulk substrate and thin film interdigital capacitors using YBa2 Cu3O7-δ (YBCO) and BaxSr 1-xTiO3. Slot capacitors made on bulk Bax Sr1-xTiO3 (BST) yielded variations in capacitance of more than 6 to 1 at 86 K with a peak electric field strength of 25 kV/cm. With a metal organic deposition (MOD) grown BaxSr1-xTiO3 300-nm overcoat on a YBCO thin film, an interdigital capacitor on LaAlO3 substrate yielded an approximate tuning range of 10% for peak field of 66 kV/cm over temperatures ranging from 50 K to 120 K 相似文献
11.
Shunyi Li Yuliang Zheng Rolf Jakoby Andreas Klein 《Advanced functional materials》2012,22(22):4827-4832
Hysteresis is induced in paraelectric (Ba,Sr)TiO3 (BST) thin‐film capacitors by inserting an Al2O3 barrier layer of a few nanometers in thickness between the BST layer and the electrode. The observed hysteresis is explained by ambipolar charge carrier injection through the Al2O3 layer and charge storage at the BST/Al2O3 interface. The magnitude of the hysteresis can be directly adjusted by manipulating the thickness ratio between BST and Al2O3. Taking into account the low loss of (Ba,Sr)TiO3 capacitors, the observed switching and retention characteristics are suitable for application as non‐volatile programmable high‐frequency devices, e.g., in radio‐frequency identification. 相似文献
12.
Al Ahmad M. Salvagnac L. Michau D. Maglione M. Plana R. 《Microwave and Wireless Components Letters, IEEE》2008,18(6):398-400
This letter reports for the first time the interesting behavior of the interface between indium tin oxide (ITO) as a high resistive electrode and barium strontium titanate tunable paraelectric thin film material. The interface is consisting of barium strontium titanate (BST) thin film dielectric material sandwiched between two ITO high resistive layers, all are integrated above glass substrate. When dc field is applied between the ITO layers, the BST thin film material properties are tuned. It is found that the ITO/BST/ITO heterostructure exhibits a tunable resistor performance. To our knowledge; these results are never reported. 相似文献
13.
Modeling the capacitive nonlinearity in thin-film BST varactors 总被引:1,自引:0,他引:1
A simple closed-form expression for the dielectric nonlinearity in thin-film high-permittivity barium strontium titanate (BST) devices is obtained from a third-order power-series expansion for the field-polarization relation. The expression is parameterized in terms of easily measurable quantities of zero-field capacitance and tuning ratio, and compares favorably with data on several representative BST compositions and device sizes. The temperature dependence of the capacitors is treated using a simple linear temperature coefficient in the zero-field capacitance that also compares favorably with experimental data on BST capacitors. The influence of interfacial ("dead" layer), fringing, and parasitic shunt capacitance on the experimental C-V curves is discussed. The results are potentially useful for circuit and electromagnetic simulation. 相似文献
14.
高度(100)取向的BST薄膜及其高介电调谐率 总被引:2,自引:0,他引:2
用脉冲激光沉积法制备(Ba1-xSrx)TiO3(x=0.35,0.50简称BST35和BST50)介电薄膜。在650℃原位退火10min,获得高度(100)取向柱状生长的晶粒。BST35薄膜的平均晶粒尺寸为50nm,BST50薄膜的晶粒尺寸为150~200nm。在室温和1MHz条件下,BST35的最大εr和调谐率分别达到810和76%,其介电调谐率高于国内外同类文献报道的数据;BST50的εr和调谐率最大分别达到875和63%。薄膜为(100)取向生长,因为薄膜沿平面c轴极化而产生应力,在电场作用下,而获得高介电调谐率。 相似文献
15.
Hongtao Xu Pervez N.K. Hansen P.J. Shen L. Keller S. Mishra U.K. York R.A. 《Electron Device Letters, IEEE》2004,25(2):49-51
Ba/sub x/Sr/sub 1-x/TiO/sub 3/ (BST) thin films have large dielectric constants that can be varied by as much as a factor of 3 with an applied field, making them attractive for radio frequency (RF) circuits as small-area ac bypass/dc blocking capacitors, or high-power varactors. However, BST must be deposited at relatively high temperatures in an oxidizing environment, presenting significant integration challenges for MMIC applications. This letter describes the successful integration of BST films on AlGaN/GaN high electron-mobility transistor (HEMT) monolithic microwave integrated circuits on sapphire substrates. A sacrificial SiO/sub 2/ buffer layer is used to protect the underlying AlGaN during the RF magnetron sputtering of the BST film at an elevated temperature, with a carefully controlled heater ramp rate to avoid degradation of the ohmic contacts on the HEMT. 相似文献
16.
介绍了一种五阶可调抽头式梳状线滤波器,设计采用共面方式接地,使用Ba0.6Sr0.4TiO3 (BST)铁电薄膜平板电容作为可调部件,并分析了平板电容结构的影响.针对梳状电调滤波器需单阶加压和外接大电阻繁琐的情况,提出利用集成在衬底上的大容量BST电容作为隔离电容,将各阶谐振器的偏压线互连来简化加压过程.运用高频电磁仿真软件HFSS进行验证,设计出的滤波器中心频率可调范围为842~960 MHz(14%),3 dB带宽为9%~10%. 相似文献
17.
通过射频磁控溅射法,采用高温溅射、低温溅射高温退火两种不同的工艺制备了钛酸锶钡(BST)薄膜。分析两种不同的工艺对BST薄膜的结构、微观形貌及介电性能的影响。采用X线衍射(XRD)分析了样品的微观结构。采用扫描电镜(SEM)和台阶仪分别测试了样品的微观形貌和表面轮廓。通过能谱分析(EDS)得到了薄膜均一性的情况。最后通过电容-电压(C-V)曲线测试得到BST薄膜的介电常数偏压特性。结果表明,与低温溅射高温退火工艺制备的BST薄膜相比,高温溅射制备的BST薄膜结晶度好,致密性高,表面光滑,薄膜成分分布较均一。因此,采用高温溅射得到的BST薄膜性能较好。在频率300 kHz时,采用高温溅射制备的BST薄膜介电常数为127.5~82.0,可调谐率为23.86%~27.9%。 相似文献
18.
水基前驱体法制备BST铁电薄膜的研究 总被引:1,自引:0,他引:1
Ba1-SrxTiO3(BST)薄膜具有非线性强、漏电流小、不易疲劳等特点,在高密度动态随机存储器的应用,受到x了极大关注。以水基溶液为前驱体,调整Ti(OC4H9)4与H2O的配比以改变溶胶的黏度,并采用旋涂法制备了BST铁电薄膜。对水基BST前驱体溶液进行了DSC/TG和XRD分析。实验表明,采用较高浓度的水基前驱体,有利于薄膜的形成和均匀性。薄膜的相结构研究表明,随着退火温度的上升,BST薄膜的结晶度上升,而晶粒尺寸随之略有下降。 相似文献
19.
Xinhua Zhu Jianmin Zhu Shunhua Zhou Zhiguo Liu Naiben Ming Shengguo Lu Helen Lai-Wah Chan Chung-Loong Choy 《Journal of Electronic Materials》2003,32(10):1125-1134
The (Ba1−xSrx)TiO3 (BST) ferroelectric thin films exhibit outstanding dielectric properties, even at high frequencies (>1 GHz), and large, electric-field
dielectric tunability. This feature makes them suitable for developing a new class of tunable microwave devices. The dielectric
properties and dielectric tuning property of BST thin films are closely related to the film compositions, substrate types,
and post-deposition process. The successful implementation of BST films as high-frequency dielectrics in electrically tunable
microwave devices requires a detailed understanding of both their processing and material properties. This paper will review
the recent progress of BST thin films as active dielectrics for tunable microwave devices. The technical aspects of BST thin
films, such as processing methods, post-annealing process, film compositions, film stress, oxygen defects, and interfacial
structures between film and substrate, are briefly reviewed and discussed with specific samples from the recent literature.
The major issues requiring additional investigations to improve the dielectric properties of BST thin films for tunable microwave
applications are also discussed. 相似文献
20.
溶胶-凝胶法制备外延Ba1-xSrxTiO3薄膜及其结构与性能研究 总被引:5,自引:0,他引:5
应用溶胶-凝胶技术在Pt/MgO(100)衬底上成功地制备了Ba0.65Sr0.35TiO3外延薄膜.XRD和SEM分析结果表明该薄膜在O2气氛中650℃热处理1h后,其(001)面是沿着Pt(100)和MgO(100)面外延取向生长的;薄膜表面均匀致密,厚度为260nm,平均晶粒大小为48.5nm.当测试频率为10kHz时,BST薄膜的介电常数和损耗因子分别为480和0.02.介电常数-温度关系测试结果表明sol-gel工艺制备的Ba0.65Sr0.35TiO3薄膜其居里温度在35℃左右,且在该温度下Ba0.65Sr0.35TiO3薄膜存在扩散铁电相变特征.当外加偏置电压为3V时,BST薄膜的漏电流密度为1.5×10-7A/cm2.该薄膜可作为制备新型非制冷红外焦平面阵列和先进非制冷红外热像仪的优选材料. 相似文献