| Summary: | 碩士 === 國防大學理工學院 === 電子工程碩士班 === 99 === In this study, we have investigated the selective wet etching technology applied on quantum well infrared photodetector (QWIP) for optical property analysis. The study focused on two major issues: one is the accuracy improvement of the etching process for optical grating pattern and the other is the calculation for absolute responsivity. In addition, we also used the proposed high selectivity etching recipe to remove the FPA substrate to achieve the better thermal imaging.
Because the etching depth of optical grating pattern is an important factor for the responsivity of quantum well infrared photodetector, we used selective wet-etching process with etching stop layer to make the etching depth of optical grating pattern more precise. The proposed method not only solves the problem that previous recipe doesn’t work because the depth of our design couldn’t be approached precisely by normal etching solutions but also enhances the spectral response for the QWIP device.
Furthermore, we proposed the modified method to achieve the correction factor that converts the relative responsivity measured from Fourier Transform Infrared Spectrometer (FTIR) into the absolute responsivity because the absolute responsivity is an important parameter to assess the QWIP performance.
Finally, we used the high selectivity etching recipe to remove the FPA substrate. It solves the problem that the thicker substrate would cause distortion of the optical crosstalk and the delamination between the FPA and ROIC due to thermal stress generated under cooling cycles to result in dead pixels and worse imaging.
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