Surface Irregularities Induced by Anodic Oxidation of n‐Type GaAs

Abstract

normalGaAs surface irregularities caused by anodic oxidation in the dark were studied by changing materials and oxidation conditions. Three different texture irregularities, pebbled appearance, lines, and a mottled color splotch, were found on the oxidized surface or the surface free of the oxide layer. For the vapor epitaxial normalGaAs with a 0.6∼3.0×1017 cm−3 carrier concentration range, only the first irregularity was observed. None of these irregularities were observed on heavily doped epitaxial or bulk normalGaAs , whereas all of them were observed on n‐type CZ material that had not been doped. Correlation to crystal defects is also discussed. It was found that pebbled texture and striations could be suppressed when anodization voltage was kept small or when electrolyte temperature was kept low.