19 November 2007 Back-illuminated GaN/AlGaN visible-blind photodiodes
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Proceedings Volume 6724, 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems; 67240I (2007) https://doi.org/10.1117/12.782514
Event: 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes, 2007, Chengdu, China
Abstract
In recent years, AlGaN semiconductor alloys, with a direct bandgap tunable between 3.4eV and 6.2eV, become the most suitable material for fabricating UV detectors. In this paper, a backside-illuminated visible-blind UV detector based on a GaN/AlGaN p-i-n heterostructure has been successfully fabricated and tested. The p-i-n photodiode structure consists of a 0.7um n-type Al0.33Ga0.67N:Si layer grown by metal-organic chemical vapor deposition (MOCVD) onto a low temperature AlN buffer layer on a polished sapphire substrate. On the top of this layer there is a 0.18um undoped GaN active layer and a 0.15um p-type GaN:Mg top layer. Square mesas of area A=1.70×10-3cm2 were obtained by inductively coupled plasma etching using BCl3, Ar and Cl2. Standard photolithographic and metallization procedures were also employed to fabricate the devices. The visible blind photodiode exhibits a narrow UV spectral responsibility band peaked at 360nm, with maximum responsibility R=0.21A/W, corresponding to an internal quantum efficiency of 82%. R0A values up to 2.64×108Ω•cm2 were obtained, corresponding to D*=2.65×1013 cmHz1/2W-1 at 360nm. The leakage current at zero bias is 5.20×10-13A. We also examined GaN/AlGaN epitaxial layers by high resolution X-ray diffraction (HRXRD). The rocking curve indicates the multiple layers including p-type layer are in good state, which indicates that the crystalline quality of films is the key of device performances.
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Liang Chen, Jun Chen, Yun Bai, Liwei Guo, Yan Zhang, Xiangyang Li, Haimei Gong, "Back-illuminated GaN/AlGaN visible-blind photodiodes", Proc. SPIE 6724, 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems, 67240I (19 November 2007); doi: 10.1117/12.782514; https://doi.org/10.1117/12.782514
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