Performance enhancement of the electron multiplication layer in EBAPS based on δ-doping

Conventional passivation layer structures for electron-bombarded active pixel sensors (EBAPS) suffer from critical performance limitations caused by significant electron energy loss and severe interfacial carrier recombination. To overcome these bottlenecks, we investigate the performance enhancement enabled by an ultrathin, heavily δ -doped structure on the surface of the electron multiplication layer in EBAPS. A comprehensive theoretical model of such structure is established in the framework of quantum tunneling and semiconductor physics. On the basis of this model, the performance of the proposed δ -doped structure is systematically compared with that of the conventional passivation layer structure, and the influences of key structural parameters, including incident electron energy, electron multiplication layer thickness, uniform doping concentration, and gradient doping depth, on the device performance parameters, such as gain, signal-to-noise ratio, and spatial resolution, are further analyzed by combining the Monte Carlo simulation method with self-consistent iterative calculation. The results demonstrate that the δ -doped structure can reduce the surface barrier and enhance the built-in electric field, thereby suppressing interfacial carrier recombination and enhancing carrier collection efficiency. The δ -doped structure outperforms the conventional passivation layer structure across all key performance metrics, while exhibiting a lower noise factor and reduced gain fluctuations. This study provides a theoretical basis for the structural design and parameter optimization of the electron multiplication layer in EBAPS.