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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
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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
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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
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Ferroelectric Ba0.65Sr0.35TiO3 (BST) thin films on the Pt/Ti/SiO2/Si substrate have been successfully prepared by sol-gel. Such films have approximately 300 nm thicknesses with a remnant polarization of about 2.95 C/cm2 and a coercive field of about 21.5 kV/cm. The investigations of X-ray diffraction and atomic force microscopy show that the BST films annealed at 650 ℃ exhibit a tetragonal structure and that the films dominantly consist of large column or grains of about 89 nm in diameter. The curves of the temperature dependence of dielectric coefficient in different frequencies display the curie transition at the temperature around 23 ℃. The dielectric loss tangent of BST thin films at 100 kHz is less than 0.04. As a result, the BST thin films are more applicable for fabrication of infrared detector compared with the BST thin films reported previously. 相似文献
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Ferroelectric Ba0.65Sr0.35TiO3(BST) thin films on the Pt/Ti/SiO2/Si substrate have been successfully prepared by sol-gel. Such films have approximately 300 nm thicknesses with a remnant polarization of about 2.95 μC/cm2 and a coercive field of about 21.5 kV/cm. The investigations of X-ray diffraction and atomic force microscopy show that the BST films annealed at 650 °C exhibit a tetragonal structure and that the films dominantly consist of large column or grains of about 89 nm in diameter. The curves of the temperature dependence of dielectric coefficient in different frequencies display the curie transition at the temperature around 23 °C. The dielectric loss tangent of BST thin films at 100 kHz is less than 0.04. As a result,the BST thin films are more applicable for fabrication of infrared detector compared with the BST thin films reported previously. 相似文献
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(Ba1—xSrx)TiO3薄膜的制备及性能的研究 总被引:10,自引:0,他引:10
选用Ba(C2H3O2)2、Sr(C2H3O2)2.1/2H2O和Ti(OC4H9)4为原材料,冰醋酸为催化剂,乙二醇乙醚为溶剂。用改进的溶胶-凝胶技术在Pt/Ti/SiO2/Si基片上成功地制备出钙钛型结构的(Ba1-xSrx)TiO3薄膜。该薄膜是制备铁电动态随机存储器、微波电容和非致冷红外焦平面阵列的优选材料;分析了薄膜的结构;测试了薄膜的介电和铁电性能。在室温10kHz下,(Ba0.73Sr0.27)TiO3薄膜介电系数和损耗分别为300和0.03。在室温1kHz下,(Ba0.95Sr0.05)TiO3薄膜剩余极化强度的矫顽场分别为3μC/cm^2和50kV/cm。 相似文献
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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
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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
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报道一种制备高性能氧化钒热敏薄膜的方法和其应用。采用反应磁控溅射薄膜沉积技术,通过改变氧化钒热敏薄膜沉积时溅射功率,从而调整钒原子在溅射出来之后接触到基片表面时的沉积速率,同时通过对设备进行改造升级,即在钒溅射腔腔外增加一个控制电源来精确控制溅射电压及氧气分压等参数来精确控制反应过程中电流密度,优化了氧化钒薄膜的制备工艺,制备出方块电阻为500 kΩ/□,电阻温度系数(TCR)为?2.7% K?1的氧化钒薄膜。实验测试结果表明,利用高性能氧化钒热敏薄膜制作的非制冷红外焦平面探测器,其噪声等效温差(NETD)降低30%,噪声降低28%,显著提升了非制冷焦平面探测器的综合性能。 相似文献
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采用射频磁控溅射法在蓝宝石基片上制备了Bi1.5Zn1.0Nb1.5O7(BZN)/Ba0.5Sr0.5TiO3(BST)双层复合薄膜,并研究了该薄膜在100 kHz~6 GHz频率范围内的介电性能。研究结果表明,BZN/BST复合薄膜的介电性能具有良好的频率稳定性。该复合薄膜的介电常数在研究的频率范围内基本与频率无关;其介电损耗在频率低于1 GHz时与频率无关,在频率高于1 GHz时随频率的上升而略微增大;薄膜在研究的频率范围内具有稳定的介电调谐率。 相似文献
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非晶硅薄膜(a-Si)是目前重要的光敏材料,在很多领域得到广泛应用。直流磁控溅射具有工艺简单.沉积温度低等优点,是制备薄膜的一种重要技术。采用直流磁控溅射工艺在玻璃基板上沉积薄膜,并对样品进行了退火处理。研究了沉积速率与溅射功率的关系。结果表明薄膜的沉积速率与溅射功率近似有线性关系。利用X射线衍射(XRD)对薄膜进行了分析鉴定,结果表明溅射的薄膜是非晶硅薄膜。利用扫描电子显微镜(SEM)对非晶硅薄膜的表面形貌进行了观察和分析,与X射线衍射测试的结果一致。所以.利用直流磁控溅射工艺能在常温下能快速制备出良好的非晶硅薄膜。 相似文献
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Tombak A. Maria J.-P. Ayguavives F. Zhang Jin Stauf G.T. Kingon A.I. Mortazawi A. 《Microwave and Wireless Components Letters, IEEE》2002,12(1):3-5
The measurement results for thin film barium strontium titanate (BST) based voltage tunable capacitors intended for RF applications are reported. At 9 V DC, BST capacitors fabricated using MOCVD (metalorganic chemical vapor deposition) method achieved 71% (3.4:1) tunability. The measured device quality factor (Q) for BST varactors is comparable with the device Q for commercially available varactor diodes of similar capacitance. The typical dielectric loss tangent was in the range 0.003-0.009 at VHF. Large signal measurement and modeling results for BST thin film capacitors are also presented 相似文献
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A PbTiO3/Ba0.85Sr0.15TiO3/PbTiO3 (PT/BST15/PT) sandwich thin film has been prepared on Pt/Ti/SiO2/Si substrates by an improved sol-gel technique. It is found that such films under rapid thermal annealing at 700°C crystallize
more favorably with the addition of a PbTiO3 layer. They possess a pure, perovskite-phase structure with a random orientation. The polarization-electric field (P-E) hysteresis
loop and current-voltage (I-V) characteristic curves reveal that a PT/BST15/PT film exhibits good ferroelectricity at room
temperature. However, no sharp peak, only a weak maximum, is observed in the curves of the dielectric constant versus temperature.
The dielectric constant, loss tangent, leakage current density at 20 kV/cm, remnant polarization, and coercive field of the
PT/BST15/PT film are 438, 0.025, 1.3 × 10−6 Acm−2, 2.46 μCcm−2, and 41 kVcm−1, respectively, at 25°C and 10 kHz. The PT/BST15/PT film is a candidate material for high sensitivity elements for uncooled,
infrared, focal plane arrays (UFPAs) to be used at near ambient temperature. 相似文献
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Jun Gou Jun Wang Weizhi Li Huiling Tai Deen Gu Yadong Jiang 《Journal of Infrared, Millimeter and Terahertz Waves》2013,34(7-8):431-436
Nano – scale metallic films have been proven to be an effective terahertz (THz) absorption layer in uncooled infrared (IR) microbolometers operated in THz spectral range. Optimized absorption can be achieved by adjusting the thickness of metallic film. Nickel – chromium (NiCr) thin films are deposited on the diaphragms of 320 × 240 VOx – based infrared focal plane arrays (IRFPA). Absorption measurements of the diaphragms with different thicknesses of NiCr (5 to 40 nm) agree reasonably well with the predicted absorption. To improve THz absorption further, a reactive ion etching (RIE) process applied to the dielectric support layer is first suggested, which generates nano – scale surface structures and increases the effective surface area of NiCr absorption film. This provides an effective way which is easy to accomplish and compatible with the manufacturing process of microbolometer IRFPAs to improve THz absorption and detection sensitivity. 相似文献