The Design of the AZO Conductive Layer on Microchannel Plate

The Design of the AZO Conductive Layer on Microchannel Plate

Citation

Yuman Wang, Shulin Liu, Baojun Yan, Ming Qi, Kaile Wen, Binting Zhang, Jianyu Gu, & Wenjing Yao. (2021). The Design of the AZO Conductive Layer on Microchannel Plate. Nanoscale Research Letters, 16(1), 55. https://doi.org/10.1186/s11671-021-03515-0 

Keywords

  • ALD-MCP
  • AZO
  • Conductive layer
  • Working resistance
  • WYM operation

Brief

This article presents a new algorithm and experimental results for adjusting the ratio of conductive and high-resistance materials in the conductive layer of an atomic layer deposition microchannel plate (ALD-MCP), specifically focusing on aluminum zinc oxide (AZO). 

Summary

The 2021 Nanoscale Research Letters article “The Design of the AZO Conductive Layer on Microchannel Plate,” by Yuman Wang et al., presents a novel design for the conductive layer of an atomic layer deposition microchannel plate (ALD-MCP) using zinc oxide (ZnO) and aluminum oxide (Al2O3). The authors argue that the conventional method of hydrogen firing to prepare microchannel plates has several drawbacks, including the inability to independently adjust the conductive and emission layers, environmental pollution, and high production costs. Atomic layer deposition (ALD) offers a more environmentally friendly and cost-effective alternative to hydrogen firing. ALD is a thin film deposition technique that uses sequential, self-limiting surface reactions to deposit materials with atomic-level precision. However, the resistivity of the AZO conductive layer must be carefully controlled, as excessively high resistance can lead to low MCP gain, while excessively low resistance can lead to overheating and breakdown.

The authors propose a novel mathematical operation, termed the WYM operation, to precisely adjust the ratio of conductive ZnO and high-resistance Al2O3 within the AZO layer. This method involves depositing alternating layers of ZnO and Al2O3 with precisely controlled thicknesses, allowing for fine-tuning of the overall resistivity of the AZO layer. The authors also introduce the concept of "working resistance", which refers to the resistance of the MCP during electron avalanche in the microchannel, and argue that this should be the primary metric for evaluating MCP resistance. They find that the working resistance of AZO-ALD-MCP is significantly lower than its non-working resistance, and decreases with increasing voltage, unlike conventional MCPs. This difference is attributed to the higher negative temperature coefficient of AZO compared to lead glass, which results in lower resistance at higher temperatures. The study demonstrates that by adjusting the ratio of ZnO and Al2O3 using the WYM operation, the working resistance of the AZO-ALD-MCP can be effectively controlled to achieve desired performance characteristics. The authors conclude that this new design method opens the way for finding better materials for the conductive layer of ALD-MCP to further improve the performance of MCPs. 

Origin: https://link.springer.com/article/10.1186/s11671-021-03515-0
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