XPS ANALYSIS OF GALLIUM NITRIDE FILM AFTER O2/BCL3 DIGITAL ETCH

Oxygen as modification gas for the first step, boron trichloride for the etch step was used to sequentially remove GaN from sapphire for 20 cycles. The relationship between oxidation and etching parameters with etching depth of each cycle was investigated. For 9 s etching time per cycle, the etch rate increased from 0.39 to 1.04 nm/cycle by increasing oxidation time from 0 to 20 s, and remained fairly constant with higher oxidation time revealing a self-limiting oxidation. The surface chemistry of GaN was investigated by X-ray photoelectron spectroscopy after ICP oxidation. A comprehensive analysis of oxygen chemisorption on GaN films with different oxidation time and possible mechanisms were discussed.