Mapping of contactless photoelectrochemical etched GaN Schottky contacts using scanning internal photoemission microscopy—difference in electrolytes

Abstract

Abstract We present the experimental results on the mapping characterization of n-type GaN Schottky contacts with selective contactless photoelectrochemical (CL-PEC) etching by using scanning internal photoemission microscopy (SIPM). The CL-PEC etching was performed in four kinds of aqueous solutions (KOH mixed with K2S2O8 (oxidant), phosphoric acid mixed with oxidant, only oxidant, and ammonia). The Schottky barrier height (qϕ B) values decreased by less than 0.1 eV in the etching with the KOH and oxidant solutions. On the other hand, the opposite trend was observed for the samples etched with the phosphoric acid solution. Whereas the samples etched with the ammonia solution had a scattered qϕ B value, they were not affected by the etching. However, the photoyield increased by 2.5–3.5 times in all kinds of etching. SIPM was found to be sensitive in visualizing the effect of the CL-PEC etching as an image.