High Quantum Efficiency AlGaN/GaN Solar-Blind Photodetectors Grown by Metalorganic Chemical Vapor Deposition

✍ Scribed by Wong, M.M. ;Chowdhury, U. ;Collins, C.J. ;Yang, B. ;Denyszyn, J.C. ;Kim, K.S. ;Campbell, J.C. ;Dupuis, R.D.

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 179 KB
• Volume: 188
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/1521-396x(200111)188:1<333::aid-pssa333>3.0.co;2-x

✦ Synopsis

We report the growth, fabrication and characterization of high-quality AlGaN/GaN solar-blind p-i-n and MSM photodetectors by low-pressure metalorganic chemical vapor deposition (MOCVD). The epitaxial layers were grown on double-polished c-plane (0001) sapphire substrates to allow for back-side illumination. The p-i-n photodiode structures typically consist of a 0.7 mm thick Al 0.58 Ga 0.42 N "window" layer, graded to a 0.2 mm thick Al 0.47 Ga 0.53 N n layer, a 0.15 mm thick Al 0.39 Ga 0.61 N i layer, a 0.2 mm thick Al 0.47 Ga 0.53 N p layer, and capped with a 25 nm GaN : Mg contact layer. At a 0 V bias, the processed p-i-n devices exhibit a solar-blind photoresponse having a maximum responsivity of 0.058 A/W at 279 nm, corresponding to an external quantum efficiency of $26%, uncorrected for reflections, etc. The MSM devices typically consist of an AlGaN x $ 0.58 window layer, and an undoped AlGaN x $ 0.44 absorbing layer. The MSMs exhibit an external quantum efficiency as high as $47% at a bias of 15 V with a peak response at 262 nm.