Formation of porous layers on InSb(100) by anodization

Abstract

The present work deals with anodization processes of n-type InSb(100). Preferential etching of InSb can be electrochemically initiated in HCl, HBr and HF solutions. Except for etch features also the formation of porous layers can be observed. The resulting features were characterized by SEM and AES measurements. Due to the narrow bandgap of the material the results of the anodization process are neither sensitive to illumination of the n-type material nor to the doping level. The morphology of the attack depends strongly on the electrochemical conditions and the type of halogen acid present in the electrolyte. In HCl and HBr a black porous layer can be formed that is likely to consist to a certain extent of an antimony-oxo-chloride or antimony-oxo-bromide. In HF, however, polarization under a wide range of electrochemical conditions leads to a uniform etching of the InSb surface.