Deep-level defects and turn-on capacitance recovery characteristics in AlGaN/GaN heterostructures |
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Authors: | Yoshitaka Nakano Yoshihiro Irokawa Masatomo Sumiya |
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Institution: | 1. Department of Electronics and Information Engineering, Chubu University, 1200 Matsumoto, Kasugai, Aichi 487-8501, Japan;2. National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan |
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Abstract: | We report on turn-on capacitance recovery measurements as a simple short-time method of evaluating carrier-trapping phenomena in a two-dimensional electron gas (2DEG) in the bulk region of AlGaN/GaN heterostructures, employing their Schottky barrier diodes. Using this technique, we have investigated an in-depth relation between deep-level defects and 2DEG carrier trapping in an AlGaN/GaN heterostructure with a GaN buffer layer containing a high C concentration. Steady-state photo-capacitance spectroscopy measurements revealed three C-related deep-level defects located at ~2.07, ~2.80 and ~3.23 eV below the conduction band in the GaN buffer layer. Additionally, turn-on capacitance recovery measurements showed a large decrease in recovery time under white-light optical illuminations with long-pass filters between 370 and 390 nm. It is concluded that the ~3.23 eV level is mainly responsible for the 2DEG carrier-trapping phenomena in the GaN buffer layer of the AlGaN/GaN heterostructure. |
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Keywords: | AlGaN/GaN heterostructures deep-level defects turn-on capacitance recovery carrier trapping GaN buffer layer |
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