Anodic Formation and Characterization of Nanoporous InP in Aqueous KOH Electrolytes

Abstract

The anodic behavior of highly doped in aqueous was investigated. Electrodes anodized in the absence of light in 2– at a constant potential of 0.5– (SCE), or subjected to linear potential sweeps to potentials in this range, were shown to exhibit the formation of a nanoporous subsurface region. Both linear sweep voltammograms and current-time curves at constant potential showed a characteristic anodic peak, corresponding to formation of the nanoporous region. No porous region was formed during anodization in . The nanoporous region was examined using transmission electron microscopy and found to have a thickness of some 1– depending on the anodization conditions and to be located beneath a thin (typically ), dense, near-surface layer. The pores varied in width from 25 to and both the pore width and porous region thickness were found to decrease with increasing concentration. The porosity was approximately 35%. The porous layer structure is shown to form by the localized penetration of surface pits into the , and the dense, near-surface layer is consistent with the effect of electron depletion at the surface of the semiconductor.