In order to explore the stability of transmissive GaAs photocathode in ultra-high vacuum system, the activation experiment and re-caesiation experiment of transmissive GaAs photocathode were carried out, and the photocurrent curves after CsO activation and after re-caesiation were tested. Experiments show that high and low temperature thermal cleaning is conducive to CsO deposition and forms a stable structure to improve the photoelectric emission capability and stability of the transmissive GaAs photocathode. Although re-caesiation activation can partially restore the photoemission efficiency of the transmissive GaAs photocathode, it will reduce the stability of the activation layer and shorten the lifetime of the transmissive GaAs photocathode.
As the rapid development of back-illuminated CMOS (BI-CMOS) image sensor technology in recent years, its application prospect in the field of Low-Light-Level (LLL) night vision has been widely concerned. Therefore, LLL imaging module was developed based on BICMOS, whose 3-D noise data was obtained under different illumination conditions. The test results show that, the signal-to-noise ratio (SNR) of imaging module becomes worse with the decreasing of illumination. According to the judgement of noise, the noise power of the image in low illumination is mainly Gaussian distribution. And the image processed by spatial filtering, which efficiently reducing the imaging noise and improving the imaging quality.
The flawed surface of GaAs/GaAlAs heterointerface after wet etching by H2O2 and NH4OH based etch ant was studied in this work. The results showed that the surface of GaAs/GaAlAs heterointerface had convex point, etching pits, pinhole, fog point, and friction scratches were investigated with a etch step measurement. And imprinting the main reasons for the formation of the etching surface defects of GaAs/GaAlAs are the poor quality of epitaxial materials, the contamination of materials surface, the unclear interface of oxidation and doping, the inhomogeneity of concentration and the operation errors. The selective etching of the GaAs/GaAlAs material eliminates some flaws and improves the quality of the etching surface of the GaAs/GaAlAs material.
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