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工作红外成像器件。当红外光照射到该器件时，热释电材料的温度升高，并通过MOS开关阵列检测到感应热释电电荷。检测到的信号通过A/D转换器送入微型计算机。通过求解热传导方程和电路方程对这种电荷输出进行了分析。从理论输出的频率依赖性可以得到最合适的结构，并制作了该器件。将约80微米的LiTaO_3板与具有64×64元件的Si MOS开关阵列放在一起。在MOS场效应管的源区形成In凸点，并通过在约150ﾟC的温度下加热将LiTaO_3与硅阵列连接。电流放大比电压放大更好，因为元件中的电荷残留量比电压放大小得多，但输出很小。其输出信号的散射比红外-CCD的要小。在微型计算机上对信号进行处理，得到了红外光斑图像。为了制作高速工作的硅单片红外成像器，还研究了低温生长PbTiO_3薄膜。生长方法是反应蒸发铅和钛。分别从不同的船上蒸发铅和钛，用质谱仪监测它们的蒸发速度，并将O_2气体吹向在约400ﾟC加热的硅和铂薄膜衬底，O_2被电离并在0.5-8keV加速。结果在400ﾟC下获得了(101)择优取向的PbTiO3薄膜，器件和制备方法的改进正在进行中。

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.