Research on electron dispersion mechanism and resolution characteristics of EBAPS

In response to the high resolution requirements of EBAPS digital low light imaging devices in military and aerospace fields, the spatial modulation transfer function is an objective method to evaluate the resolution of liner photoelectric imaging system. on the basis of the existing GaAs photocathode and CMOS structure, a five-part MTF model of EBAPS devices were constructed using modulation transfer function theory. It was proposed that the electron dispersion and scattering characteristics during electron transmission are the main factors causing the decrease in resolution. We studied the dispersion characteristics of near-field photoelectrons based on the physical model of near-field focusing. Based on the theory of low energy electron solid interaction, we combined Monte Carlo simulation methods to derive and simulate the electron transit and scattering characteristics of the passivation layer. Based on the theory of electron diffusion and drift in semiconductors, We constructed a CMOS electron transport model to analyze the electron transport diffusion characteristics. Finally, the electron dispersion and scattering mechanism of EBAPS is revealed, and the MTF model of EBAPS is established, which is composed of near-field dispersion, CMOS transport diffusion and CMOS chip. Moreover, by optimizing the proximity process parameters to realize the device preparation, the ultimate resolution of EBAPS was increased from 22lp/mm to 32lp/mm. It is pointed out that backscatter dispersion of incident electrons on the CMOS surface is a key method to further improve resolution. This has important guiding significance for the future development of high-resolution EBAPS devices.