Charge relaxation and gain depletion for candidate secondary electron emission materials

Microchannel plates (MCPs) are widely used in photodetectors with a picosecond resolution. Two main characteristics of MCPs, gain and timing resolution, strongly depend on the materials parameters, as well as on the history of electron avalanche evolution. The most important effect that can significantly change the efficiency of an MCP is the effect of saturation of the electronic current, which occurs at high-level input signals. In this paper, the saturation effects are studied numerically, as they are applicable to analysis of large-area, fast photodetectors. It is shown that the saturation effect for short pulses can be reduced by introducing a thin, resistive layer between the bulk material and the emissive coating. The gain and time resolution dependencies on the pore size and voltage are studied numerically. The results are compared with the simulations of other authors and available experimental data.