Oxidation and etching behaviors of the InAs surface in various acidic and basic chemical solutions

Indium arsenide (InAs) is the candidate of choice as a new channel material for application in future technologies beyond the Si–based electronic devices because it has a much higher electron mobility than silicon. In this study, the oxidation and etching behaviors of InAs (100) in various acidic and basic solutions, such as HF, HCl, H₂SO₄, NaOH, KOH, and NH₄OH, were investigated. In addition, the effect of pH on the oxidation and etching reactions taking place on the InAs surface was studied using solutions with a pH ranging from 1 to 13. It was observed that the oxidation of the InAs surface was hindered in acidic solutions, which was attributed to the dissolution of the oxidized surface layer. In particular, the treatment of the InAs surface using a strongly acidic solution with a pH of less than 3 produced an oxide–free surface due to the predominant etching of the InAs surface. The addition of H₂O₂ to the acidic solutions greatly increased the etching rate of the InAs surface, which suggests that the oxidation process is the rate–limiting step in the sequence of reactions that occur during the etching of the InAs surface in acidic solutions. The etching of InAs was suppressed in neutral solutions, which resulted in the formation of a relatively thicker oxide layer on the surface, and mild etching of the InAs surface took place in basic solutions. However, in basic solutions, the addition of H₂O₂ did not significantly contribute to the increase of the oxidation state of the InAs surface; thus, its effect on the etching rate of InAs was smaller than in acidic solutions.