Optimum design of electron bombarded active pixel sensor for low-level light single photon imaging

Low-Level Light Imaging(LLLI) devices are now been widely used in military, astronomy, scientific, and even in surveillance for our daily uses. The traditional devices like ICCD, EBCCD, EMCCD, which either complicated in structure or require extra cooling system. However, a novel device called Electron Bombarded Active Pixel Sensor(EBAPS) has been developed, it is a proximity focused device which lead photoelectrons produced by photocathode hitting directly towards back illuminated CMOS and cause the semiconductor bombard phenomenon to amplification and then being readout. EBAPS is relatively small in size, less weight, with high sensitivity, and can be used to detect single photon event, etc. Although it has been proven to have excellent sensitivity in the field of LLLI, the performance today is still considered far from its maximum potential. Here, we modeled the structure of EBAPS and studied the factors influencing the performance of the device. By selecting proper parameters like proximity distance, acceleration voltage, photocathode quantum efficiency, etc., we achieved the single photon image mode with a satisfactory sensitivity. Besides, we simulated the electron scattering trajectories among the semiconducting multiplication area by using Monte Carlo method, we compared the simulation results in different conditions and successfully in finding the optimum parameter, which achieved a relatively high sensitivity. The simulation results in this paper could have a profound theoretical foundation in developing higher gain EBAPS.