Opaque gallium nitride photocathodes in UV imaging detectors with microchannel plates
Opaque gallium nitride photocathodes in UV imaging detectors with microchannel plates
复制标题
DOI：
10.1117/12.2025185
复制
发表时间：
2013-09
期刊：
影响因子：
--
通讯作者：
A. Tremsin;J. Hull;O. Siegmund;J. McPhate;J. Vallerga;A. Dabiran;A. Mane;J. Elam
中科院分区：
文献类型：
--
作者：
A. Tremsin;J. Hull;O. Siegmund;J. McPhate;J. Vallerga;A. Dabiran;A. Mane;J. Elam
本文介绍了一种新型微通道板（mcp）上直接沉积不透明氮化镓（GaN）光电阴极的优化和性能。新型硼硅酸盐玻璃mcp是在原子层沉积的帮助下制造的，可以承受更高的温度，从而可以在其表面直接沉积GaN膜。在~200 ~ 400 nm的光谱范围内，研究了生长在不同表面层（如Al2O3或缓冲AlN层）上的mbe生长的不同厚度和缓冲层的GaN光电阴极的量子效率，以确定最佳的不透明光电阴极结构。通过表面终止激活具有GaN光电阴极的mcp，以实现有效光子探测的负电子亲和。当光电阴极沉积在输入窗口上时，与半透明结构相比，不透明光电阴极能够显着拓宽光谱灵敏度范围。本文还介绍了目前研制的不透明GaN光电阴极密封管事件计数检测器的设计。实验表明，对于具有高空间分辨率（大于50 μm）、时间分辨率<100 ps、极低背景水平（只有少数事件cm-2 s-1）的事件计数MCP探测器，虽然仍有开发工作需要，但在200-400 nm范围内的探测量子效率应达到20%以上，在100-200 nm范围内的探测量子效率应达到50%以下。
The optimization and performance of opaque Galium Nitride (GaN) photocathodes deposited directly on novel Microchannel Plates (MCPs) are presented in this paper. The novel borosilicate glass MCPs, which are manufactured with the help of Atomic Layer Deposition, can withstand higher temperatures enabling direct deposition of GaN films on their surfaces. The quantum efficiency of MBE-grown GaN photocathodes of various thickness and buffer layers was studied in the spectral range of ~200-400 nm for the films grown on different surface layers (such as Al2O3 or buffer AlN layer) in order to determine the optimal opaque photocathode configuration. The MCPs with the GaN photocathodes were activated with surface cesiation in order to achieve the negative Electron Affinity for the efficient photon detection. The opaque photocathodes enable substantial broadening of the spectral sensitivity range compared to the semitransparent configuration when the photocathodes are deposited on the input window. The design of currently processed sealed tube event counting detector with an opaque GaN photocathode are also described in this paper. Our experiments demonstrate that although there is still development work required the detection quantum efficiencies exceeding 20% level should be achievable in 200-400 nm range and <50% in 100-200 nm range for the event counting MCP detectors with high spatial resolution (better than 50 μm) and timing resolution of <100 ps and very low background levels of only few events cm-2 s-1.