CONTROL OF SURFACE MORPHOLOGY IN PHOTOELECTROCHEMICAL ETCHING OF GaN

摘要

Several mechanisms for morphology control in PEC etching have been investigated. The dependence of surface morphology on photoelectrochemical (PEC) process conditions is reported. Considerable control over surface roughness can be exerted through selection of the electrolyte concentration, illumination intensity, as well as through the use of an applied bias voltage during the PEC etch process. The underlying physical mechanisms governing etch behavior and morphology are explored, and provide insights for selecting process conditions. A combination of oxide-mediated PEC etching in lower-concentration electrolytes and bias-enhanced etching has been found to produce the smoothest surfaces.