A Solar-Blind AlGaN-Based p-i-n Back-Illuminated Photodetector with a High Temperature AlN Template Layer

The growth, fabrication, and characterization of a solar-blind A1GaN-based p-i-n back-illuminated photodetector with a high temperature A1N template are reported for the first time. The photodetector was fabricated from multilayer AIx Gal-xN films grown by MOCVD on double-polished c-plane （0001） sapphire substrates. Crack free, high A1 content （0.7） A1GaN multilayer structure,designed for the solar-blind p-i-n back-illuminated photodetector,was grown on a high temperature A1N template without a nuclear layer. The high quality of the epitaxial layers is demonstrated by in-situ optical reflectance monitoring curve, triple-axis X-ray diffraction, and atomic-force microscope. At a 1.8V bias, the processed p-i-n photodetector exhibits a solar-blind photoresponse with a maximum responsivity of 0. 0864A/W at 270nm. The photodetector exhibits a forward turn-on voltage at around 3.5V and a reverse breakdown voltage above 20V, and the leakage current is below 20pA for 2V reverse bias.

球载大面积Phoswich能量分辨率研究

对混合型球载硬Ｘ射线天文望远镜（ＨＡＰＩ－４）的ＰｈｏｓｗｉｃｈＮａＩ（Ｔｌ）／ＣｓＩ（Ｎａ）探测器的能量分辨率进行了研究。实测表明，光电倍增管光阴极面响应的非均匀性与入射光谱有关，用蓝色滤光片所测非均匀性小于２０％。采用对晶体窗玻璃进行罩膜处理，改变荧光收集条件，以牺牲幅度换取均匀性对能量分辨率的改善效果是十分明显的，可将Ｐｈｏｓｗｉｃｈ探测器能量分辨率从４５％（６０ｋｅＶ）提高到２４％。此外，对几种光学耦合材料也进行了测量比较。