Abstract
Normally-off AlGaN/GaN HEMTs have been fabricated by employing a recessed-gate structure and oxygen plasma treatment and outstanding improvement of V th variation is observed. The origin of the observed positive V th shift and reduced variation window induced by oxygen plasma treatment is investigated by computational methods. Formation energy calculations for oxygen inclusions in III–N reveal that a negatively charged V Al -O N complex in the AlGaN passivation layer can be a major source of V th variation in AlGaN/GaN hetero-structured devices. Calculated trap energy levels are used as the parameters of a device simulation, which indicated that significant V th variation can be induced by a small fluctuation in the AlGaN layer thickness and defect densities. Our theoretical investigation shows that normally-off AlGaN/GaN HEMTs having reliable V th variation can be produced by oxygen inclusions accompanying a recessed-gate structure.
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Hong, KH., Choi, H.S., Hwang, I. et al. Effects of oxygen plasma treatment on V th uniformity of recessed-gate AlGaN/GaN HEMTs. Electron. Mater. Lett. 10, 363–367 (2014). https://doi.org/10.1007/s13391-013-3216-x
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DOI: https://doi.org/10.1007/s13391-013-3216-x