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Proceedings Paper

Back-illuminated GaN/AIGaN visible-blind photodiodes
Author(s): Liang Chen; Jun Chen; Yun Bai; Liwei Guo; Yan Zhang; Xiangyang Li; Haimei Gong
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Paper 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.

Paper Details

Date Published: 19 November 2007
PDF: 5 pages
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
Show Author Affiliations
Liang Chen, Shanghai Institute of Technical Physics (China)
Jun Chen, Shanghai Institute of Technical Physics (China)
Yun Bai, Shanghai Institute of Technical Physics (China)
Liwei Guo, Institute of Physics (China)
Yan Zhang, Shanghai Institute of Technical Physics (China)
Xiangyang Li, Shanghai Institute of Technical Physics (China)
Haimei Gong, Shanghai Institute of Technical Physics (China)


Published in SPIE Proceedings Vol. 6724:
3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems
Sen Han; Tingwen Xing; Yanqiu Li; Zheng Cui, Editor(s)

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