Effect of atomic layer deposited aluminium oxide films on electrical properties of lead silicate glass microchannel plate

Microchannel plate (MCP) is an important signal multiplier. The original reduced lead silicate glass MCP was coated with amorphous alumina by atomic layer deposition (ALD), using trimethylaluminium Al(CH₃)₃(TMA) and water as precursors, to enhance the electron gain characteristics. The electrical properties of ALD-MCP at different deposition temperatures, cycles and annealing processing were investigated. The results indicated that the electron gain showed a Bigaussion trended electron gain-deposition temperature behavior at the ALD deposition temperature controlled from 120°C to 300°C with 60 deposition pulse cycles of TMA/H₂O, while, the bulk resistances of which were basically unchanged. Moreover, the optimum deposition cycles were increased at the maximum electron gains with the rising deposition temperature. Besides, the modified effect of ALD-MCP was significantly affected by the processing parameters, the electrical properties of which even deteriorated with the unsuitable one. The electron gain and dark current was mainly related to the concentration of hydroxyl on the surface of microchannel layer. With an excessive annealing temperature at 400°C, despite the electron gain of ALD-MCP was almost 2×10⁴ , the dark current of which would increase dramatically, even more than four times larger than that of the original hydrogen reduced MCP.