The electronic properties, surface chemistry and surface morphology of plasma-treated n-Al0.4Ga0.6N were studied using electrical contact measurements, atomic force microscopy and X-ray photo-emission spectroscopy. It was noted that, although excessive etching could cause the surface roughness to increase significantly, the nitrogen vacancies, VN, produced by the excessive etching could be compensated by the negative effects of the rougher surface. Thus, the VN produced by excessive etching played a key role in the ohmic contact of high-Al AlGaN and could reduce ohmic contact resistance. The effect of rapid thermal annealing upon the performance of n-Al0.4Ga0.6N could significantly reduce the damage caused by excessive etching.

Effects of Different Plasma Energy Treatments on n-Type Al0.4Ga0.6N Material. L.Yang, Y.Hao, X.W.Zhou, X.H.Ma: Chinese Physics Letters, 2009, 26[7], 077105