Development of Room-Temperature-Operated Infrared Imaging Device

研制了一种热释电材料与硅MOS开关阵列相结合的室温红外成像器件。当红外光照射到器件时，热释电材料的温度升高，通过MOS开关阵列检测感生的热释电电荷。检测到的信号通过A/D转换器输入微机。通过求解热传导方程和电路方程分析了这种电荷输出。从理论输出的频率依赖性得到了最合适的结构，并制作了器件。将80 μ m左右的LiTaO_3板与64 × 64单元的Si MOS开关阵列放在一起。在MOS FET的源极区形成In凸块，并通过在约150 ℃加热将LiTaO_3与Si阵列连接。制作的器件通过施加6种脉冲进行垂直和水平扫描来驱动。信号的电流放大优于电压放大，因为元件中的电荷残留比电压放大小得多，但输出相当小。输出显示出比IR-CCD更小的信号散射。在微机上对信号进行处理，得到了红外光斑图像。研究了PbTiO_3薄膜的低温生长，以制备高速工作的硅单片红外成像器。生长方法是Pb和Ti的反应蒸发。Pb和Ti从不同的舟中蒸发，它们的蒸发速率用质谱仪监测，O_2气体吹到加热到400 ℃左右的Si和Pt薄膜衬底上。O_2在0.5-8 KeV电离加速。结果表明，在400 ℃时，获得了（101）取向的PbTiO_3薄膜。目前正在对器件和制造方法进行改进。

Room-temperature-operated infrared imaging device, which is a combination of pyroelectric material and Si MOS switch array, has been developed. When infrared light irradiate the proposed device, temperature of the pyroelectric material is raised up, and induced pyroelectric charges are detected through the MOS switch array. The detected signal is taken into a microcomputer through an A/D converter. This charge output has been analyzed by solving thermal conduction and electrical circuit equations. The most adequate structure could be obtained from frequency dependence of the theoretical output and the device was fabricated. LiTaO_3 plate of about 80 micrometers are put together with the Si MOS switch array having 64x64 elements. In bumps are formed on the source areas of the MOS FETs, and connect the LiTaO_3 with the Si array by heating up at about 150ﾟC. Fabricated device was driven by applying 6 kinds of pulses for vertical and horizontal scannings. Current amplification of the signal is preferable to the voltage amplification as charge residues in the elements are much smaller than the voltage amplification, but the the output is pretty small. The output shows smaller scattering of the signal than that of the IR-CCD. An infrared spot image has been obtained by processing the signal in a microcomputer. Growth of PbTiO_3 thin film at low temperature has been also studied to fabricate Si-monolithic infrared imager operated at high speed. The growth method is reactive evaporation of Pb and Ti. Pb and Ti were evaporated from separate boats, their,evaporation rates were monitored by a mass-spectrometer, and O_2 gases were blown to the Si and Pt film substrates heated at about 400ﾟC. O_2 were; ionized and accelerated at 0.5-8 KeV. Resultantly, (101)-oriented PbTiO_3 thin films have been obtained at 400ﾟC. Improvement of the device and the fabrication method are now in progress.