Progress in atomic layer deposition based microchannel plate

Abstract

Microchannel plate (MCP) is well known as the core component of image intensifiers and particle detectors. Atomic Layer Deposition (ALD), a powerful and precise thin film deposition technique, has been applied to improve the performance of MCPs by surface modification. In this study, ALD processes for both secondary electron emission (SEE) coatings and resistive coatings on MCPs has been investigated. Al2O3 films were deposited by ALD on traditional MCPs as SEE layers, and aluminum-doped zinc oxide (AZO) films were deposited on white MCPs (MCPs without firing hydrogen) as the resistive layer. The SEM results show good uniformity of the ALD layers inside MCP channels. We have made a preliminary exploration on the relationship between gain of MCP, thickness of SEE layer and reaction temperature. The gain of traditional MCPs with aspect ratio of 39:1 increases from 3200 to 14000 (@Bias Voltage = 800V) by coating a SEE layer under a specific condition. Additionally, the aging experiment result indicates that the liftime of MCPs (from 0.15C to 0.29C) has been extended. The resistance of MCPs can be tuned by changing the doping ratio and thickness of resistive layer. We have successfully found several ALD processes for the resistive coatings, which can control the resistance in the suitable range of MCPs (about 100MΩ@800V). The volt-ampere characteristics of MCP with resistive layer is approximately exponential function relation, which differ with traditional MCPs.