Study on degradation mechanism of equivalent background illumination in image intensifiers based on interface characteristics of p-GaAs materials

Equivalent Background Illumination (EBI) is a core metric for evaluating the imaging quality and noise performance of low-light image intensifiers, whose degradation directly limits the operational stability and service life of devices. As the activation layer of photocathodes in low-light image intensifiers, p-type GaAs and its contact interface with electrodes are the key factors regulating EBI performance. Focusing on the p-GaAs/Cr contact interface, this paper systematically investigates the influence mechanism of GaAs interface characteristics on EBI degradation. Combining experimental tests and finite element simulation, we clarify that the electro-thermal coupling effect dominated by contact resistance variation is the core pathway of EBI degradation. The results show that the surface doping concentration and oxide layer of p-GaAs modify the metal-semiconductor contact resistance by adjusting the depletion region width, which further induces Joule heat accumulation and local thermal concentration at the interface and ultimately leads to EBI degradation of the device. This study provides theoretical and experimental support for EBI performance optimization, structure design, and reliability improvement of low-light image intensifiers.