Surface analysis of n‐GaN crystal damaged by RF‐plasma‐etching with Ar, Kr, and Xe gases

Abstract

AbstractTo understand the etching phenomenon or preferential etching in the GaN crystal that consisted of two elemental atoms, dry etchings were carried out using rare gases with a simple structure. n‐type GaN crystals were RF‐plasma‐etched with Ar, Kr, and Xe gases at various gas pressures and etching times. The etched surfaces were analysed with the XPS method. The surface composition (N/Ga ratio) of the samples etched at Ar pressure of 10 mTorr and 200 mTorr almost agreed with the calculation values of the plasma particle model (PIS). N/Ga ratio of Ar etched sample at the pressure of 50 – 100 mTorr was approximately one and did not agree with the PIS calculation. This discrepancy seems to be related to the pit‐like defect formation at the pressure range. The values of the N/Ga ratio of the samples etched with Kr and Xe gases were approximately one and did not agree with the theoretical PIS calculation, which predicts N/Ga > 1. This discrepancy may have occurred by N2 molecule formation with excess N atoms, and which may have been desorbed from the surface. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)