MORPHOLOGY AND STRONGLY ENHANCED PHOTORESPONSE OF GAP ELECTRODES MADEPOROUS BY ANODIC ETCHING

Single crystalline n-type GaP was made porous by anodic etching in the dark in sulfuric acid solution. The morphology and (photo)electrochem ical properties of the porous layer were investigated. Submicron pits 10 to 30 mu m apart were formed at the surface. Below the surface, the pits acted as the nuclei of distinct porous domains. Pore widths and pore wall thicknesses were approximately 100 nm. The creation of the p orous layer caused the quantum yield for light-to-current conversion t o increase from extremely low values to unity for light absorbed in th e indirect optical transition. The mechanism of pore formation and the striking opto-electrical properties of porous GaP are discussed.