Study Of The Effect Of Electron Multiplication Layer Backscattering On Gain And Noise

Electron Bombardment Complementary Metal Oxide Semiconductor(EBCMOS)as a new type of micro-optical night vision sensor technology,in recent years,because of its high detection sensitivity,low cost,fast response time,small size,can work in ultra-low illumination and many other advantages,has become the mainstream of the development in the field of micro-optical night vision in the future.The current domestic research is mainly focused on the charge collection efficiency and secondary electron gain in the electron multiplication layer,and there is less research on the characteristics of backscattered electrons.After electrons are incident into the electron multiplication layer,backscattered electrons are generated on the surface,and the backscattered electrons are re-incident into the passivation layer by the electric field,which leads to the generation of additional noise and thus the degradation of imaging quality.This paper focuses on the factors affecting the characteristics of backscattered electrons and the effect of backscattered electrons on gain and signal-to-noise ratio.First,starting from the principle of the interaction between low-energy electrons and solid matter,Monte Carlo simulation is used to simulate the scattering process of electrons in the electron multiplication layer,and a theoretical calculation model of the electron backscattering trajectory is established to study the influence of the surface structure of the electron multiplication layer and the energy and diameter of the incident photoelectrons on the characteristics of the backscattered electrons.Next,the distribution of the incident electron multiplication was calculated based on the scattering characteristics of the incident electrons.The backscattered electrons were analyzed in terms of their drop point distribution,energy distribution and incident angle distribution when they were re-incident into the passivation layer by the electric field,and the multiplication distribution of backscattered electrons re-incident into the electron multiplication layer was obtained.Finally,the charge collection efficiency model for the case of uniform doping of the substrate is established according to the carrier theory,and the signal-to-noise ratio calculation model is established according to the detector noise theory.The effects of doping concentration,incident photoelectron energy and electron multiplication layer thickness on the charge collection efficiency,gain and signal-to-noise ratio are simulated.And the charge collection efficiency,gain and signal-to-noise ratio with and without backscattered electrons are also compared to reveal the effect of backscattered electrons on gain and signal-to-noise ratio,which provides theoretical support for the subsequent preparation of high-performance EBCMOS devices in the process.