Spectral response characteristics of the transmission-mode aluminum gallium nitride photocathode with varying aluminum composition

Hao Guanghui; Liu Junle; Ke Senlin

摘要

In order to research spectral response characteristics of transmission-mode nanostructure aluminum gallium nitride (AlGaN) photocathodes, the AlGaN photocathodes materials with varied aluminum (Al) composition were grown by metalorganic chemical vapor deposition (MOCVD) and its optical properties were measured. The Al compositions of each AlGaN film of the photocathodes were analyzed from their adsorption properties curves; their thickness was also calculated by the matrix formula of thin-film optics. The nanostructure AlGaN photocathodes were activated with the Caesium-Oxygen (Cs-O) alternation, and after the photocathode was packaged in vacuum, their spectrum responses were measured. The experimental results showed that the trend of spectrum response curves first increased and then decreased along with the increasing of the incident light wavelength. The peak spectrum response value was 17.5 mA/W at 255 nm, and its quantum efficiency was 8.5%. The lattice defects near the interface of the AlGaN heterostructure could impede the electron motion crossing this region and moving toward the photocathode surface; this was a factor that reduces the electron emission performance of the photocathodes. Also, the experimental result showed that the thickness of each AlGaN layer affected the electron diffusion characteristics; this was a key factor that influenced the spectrum response performance. (C) 2017 Optical Society of America

机译：为了研究透射模式纳米结构铝氮化铝（AlGaN）光电量的光谱响应特性，通过金属有机化学气相沉积（MOCVD）生长具有变化的铝（Al）组合物的AlGaN光电阴离子材料，并测量其光学性质。从它们的吸附性能曲线分析光常数的每个AlGAN膜的Al组合物;它们的厚度也通过薄膜光学器件的基质公式计算。用铯 - 氧（CS-O）交替激活纳米结构AlGaN光电偶，并且在真空中封装光电阴极后，测量它们的光谱响应。实验结果表明，光谱响应曲线的趋势首先增加，然后随着入射光波长的增加而降低。峰值谱响应值为17.5mA / W，255nm，其量子效率为8.5％。在AlGaN异质结构的界面附近的晶格缺陷可能妨碍交叉该区域并朝向光电阴极表面移动的电子运动;这是降低光电量的电子发射性能的因素。此外，实验结果表明，每个AlGAN层的厚度影响了电子扩散特性;这是影响光谱响应性能的关键因素。（c）2017年光学学会

Spectral response characteristics of the transmission-mode aluminum gallium nitride photocathode with varying aluminum composition

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