关键词:
Electron multipliers
摘要:
Objective Electron bombardment CMOS (EBCMOS) is an advanced micro-optical imaging technology. The back-side bombarded CMOS (BSB-CMOS) imaging chip, when integrated with electron bombardment imaging systems, facilitates digital imaging of targets under extremely low illumination conditions. EBCMOS is better than traditional micro-optical imaging devices considering it combines high gain and signal-to-noise ratio (SNR) of vacuum devices with rapid response, miniaturization, and digital output and transmission features of solid-state devices. This chip advancement offers considerable potential in military applications, single-photon detection, and medical imaging, among others. The EBCMOS structure primarily has BSB-CMOS, a photocathode, and a vacuum tube. The noise characteristics of EBCMOS devices are affected by various factors, such as dark current, readout, photon, and multiplication noises;among these, dark current plays a critical role in determining the imaging quality of EBCMOS, especially under low light conditions. Methods This study presents a comprehensive analysis of noise sources and their influencing factors in the EBCMOS imaging system based on the operational principles of an EBCMOS. A theoretical model for SNR calculation was developed by incorporating the existing EBCMOS gain model. The roles of the passivation and electron multiplication layers in the dark current generation in EBCMOS devices is emphasized. Key parameters, including the SNR within a pixel, the number of total noise electrons within a pixel (Npixel), the number of multiplying electrons (NM) within a pixel, and the number of dark current electrons per unit pixel (Ndark), describe the noise characteristics. The simulations examined the effects of various passivation layer materials, passivation layer thickness, incident electron energy, and substrate temperature on these noise characteristics. This study provides a theoretical foundation for the development of low-noise and high-perfo