【作者】 何少伟；

【导师】 王兴治； 易新建；

【作者基本信息】 华中科技大学 ， 物理电子学， 2008， 博士

【摘要】 高灵敏度的非致冷红外焦平面的出现被认为是近二十多年来红外工程的最了不起的成就。相比于致冷型光子探测器,非致冷型探测器具有成本低、体积小、重量轻、功耗小、可靠性高等方面的优点,引起了红外成像应用方面的广泛的关注。氧化钒微测辐射热计是一种非致冷红外热探测器,它采用与标准的互补型金属氧化物半导体(Complementary Metal Oxide Semiconductor-CMOS)工艺兼容的表面微机械加工工艺,将阵列探测器与读出电路单片集成。目前已有像元面积25μm×25μm、阵列规模640×480的氧化钒微测辐射热计,其噪声等效温差接近12mk。但是微测辐射热计的性能改善还有很大的空间,特别是改善热敏材料的性能。本文围绕微测辐射热计通常使用的材料二氧化钒(Vanadium Dioxide-VO2)进行研究,制备了微米及纳米结构VO2薄膜,研究了两种材料的性能,重点对两种材料在红外探测方面的应用进行了研究。主要的研究成果如下:(1)进行了微米结构VO2薄膜研制工作。通过磁控溅射方法制备的该薄膜具有1~2μm平均晶粒度,相变温度为68℃,在半导体区的电阻温度系数(Temperature coefficient of Resistance-TCR)为-2.2%/K。(2)开展了纳米结构VO2薄膜研究工作。该薄膜通过离子束溅射和后退火工艺制备,对薄膜的特性研究表明:薄膜晶粒度为8nm,35℃发生相变,在材料的半导体相区TCR为-7%/K,较微米结构热敏VO2的TCR高3倍多。(3)制作了微米及纳米VO2线列128元红外探测器,并对两者的红外探测性能进行了对比测试。测试结果表明:纳米VO2线列探测器的红外响应性能较微米VO2线列探测器的红外响应性能得到了很大的提高,前者为后者的2~3倍。(4)研制了以微米VO2薄膜为传感材料,聚合物苯并环丁烯(Benzocyclobutene- BCB)为柔性衬底的柔性微测辐射热计。对器件的测试表明:在800K的黑体辐照、3Hz斩波频率下,器件的响应率和探测率分别为7.4×103V/W和6.9×107cmHz1/2/W。(5)完成了微米VO2阵列(32×32)微测辐射热计的研制工作,器件的制作工艺与CMOS工艺完全兼容。测试表明:在1V的偏压下,器件的像元响应率和噪声等效功率的典型值分别为1.47×104 W/K、4.14×10-10W。(6)研究了低温相变纳米VO2薄膜智能窗在可见光区低透过率的改善方法。通过在纳米VO2智能窗上镀SiO2减反膜的方法取得了较好的试验效果,使智能窗在VO2薄膜半导体相和金属相的可见光区透过率都有不同程度的改善。更多还原

【Abstract】 The appearance of high-sensitivity uncooled infrared focal plane arrays is considered as the most significant achievement in IR engineering during the last twenty years. The devices have recently gained broad attention for infrared imaging applications, due to their advantages such as low cost, light weight, low power, wide spectral response, and long term operation compared to cooled photon detectors.Microbolometer is a type of uncooled infrared thermal detectors. It uses a surface-micromachined process to integrate heat-sensitive detector arrays with CMOS read-out IC. Currently, microbolometer arrays based on VOx heat-sensitive material have been fabricated with 640×480 array formats and 25μm×25μm pixel sizes, and the NETD approaches 12mk. However, there is still amounts of room to improve the performance of these devices through improving the properties of the heat-sensitive material.In this dissertation, the fabrication and performance of microstructure and nanostructure heat-sensitive VO2 thin films for microbolometer are presented. The major work is to investigate the applications of the two kinds of VO2 thin films on infrared detectors, described as followings.(1) Conventional microstructure VO2 thin films have been fabricated by DC magnetic sputtering. The phase transition temperature for as-fabricated heat-sensitive VO2 films with the grain size of 1~2μm is around 68℃, and the TCR of this heat-sensitive material is about -2.2%/K in the semiconductor region.(2) Novel nanostructure VO2 thin films are prepared using reactive ion beam sputtering and post annealing. The phase transition temperature for the nano-VO2 films with the grain size of 8~10 nm is 35℃. The TCR of this heat-sensitive material is about -7%/K in the semiconductor region, which is more than 3 times higher than that of the conventional microstructure VO2 thin films.(3) Linear infrared sensors with 128 elements based on both the nanostructure VO2 thin films and the conventional microstructure VO2 thin films are fabricated with the same design, respectively. The comparative tests of the two kinds of sensors are conducted. The results of the tests show that the performance of the device based on the nanostructure VO2 thin film is improved greatly compared with the device based on the conventional microstructure VO2 film. The former is 2~3 times better than the latter.(4) The flexible microbolometers based on the microstructure VO2 thin film are fabricated on bisbenzocyclobutene (BCB) substrates. The test results show that the responsivity and the detectivity of the device at the black body temperature of 800K and with the chopper frequency of 3Hz are 7×103V/W and 7×107cmHz1/2/W, respectively.(5) The 32×32 microbolometer array are fabricated based on the microstructure VO2 thin films. The responsivity of 1.47×104 V/W and the NEP of 4.14×10-10 W are obtained at a pulse bias of 1V.(6) The improvement of the low transmittance in the visible region of the smart window based on the low-temperature phase transition nanostructure VO2 thermochromic thin films is studied. A decent result is obtained by coating a SiO2 anti-reflection layer on nanostructure VO2 smart window. The transmittances of the smart window of the VO2 thermochromic thin films at both the semiconductor phase and the metallic phase are improved to some degree.更多还原