Photoinduced oxide film formation on n-type GaN surfaces using alkaline solutions

We report on photoassisted wet chemical formation of thin oxide films on n-GaN layers in potassium hydroxide based electrolytes at room temperature. The kinetics of the oxide formation and dissolution were examined via photocurrent transients. The tendency of the photocurrent to level out during photoelectrochemical etching experiments is associated with a quasiequilibrium state at the semiconductor/electrolyte interface. Homogeneous oxide films were grown in weak alkaline solutions (11 < pH < 13) under potentionstatic control with oxidation rates of up to 250 nm/h and characterized by Auger electron spectroscopy. Consequences on wet photochemical etch strategies are discussed. (C) 2000 American Institute of Physics. [S0003-6951(00)00826-3].