Etch Pit Observation of Very Thin {001}-GaAs Layer by Molten KOH

Abstract

The etching rate on a {001} plane of GaAs in molten KOH as the etchant is examined in order to reveal etch pits corresponding to dislocations for thin GaAs layers. The mean etching rates were 0.083 µm/min. and 0.98 µm/min. at 300°C and 350°C, respectively. It was found that the etching thickness of about 0.3 µm was sufficient to reveal the dislocation structure. This etching method using molten KOH is applicable to the examination of the correlation between dislocations in epitaxially grown thin layers and those in the substrates. Most dislocations propagate from the substrate to the epitaxial layers, whereas some parts of dislocations disappear in the epitaxial layers and the others are generated in the epitaxial layers.