Pore Formation in p-type Gallium Phosphide through Chemical Etching

Abstract

P-type gallium phosphide can be used as an electrode for the electrochemical reduction of carbon dioxide. As the reaction takes place on the electrode surface, maximizing the surface area of the crystal would enable the reaction to proceed at a higher rate. Electrochemical techniques which have resulted in pore formation on other semiconductors have not been successful with p-GaP. Therefore, chemical etches are employed instead. Crystals exposed to several of the solutions tested exhibited altered topographies as compared to unetched crystals when examined with a scanning electron microscope. The altered topographies were either very smooth or appeared to be porous. Solutions which cause porous topography feature strong oxidizing agents which likely selectively attack the phosphorus in the crystal, resulting in non-uniform dissolution of the crystal and pore formation.