Investigations on Electrode-Less Wet Etching of GaN Using Continuous Ultraviolet Illumination
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Dry etching of GaN-based devices can introduce damage onto exposed layers of the semiconductor. In this paper, electrode-less wet etching of nominally undoped GaN is investigated in terms of light intensity, solution concentration, and mask geometry in order to determine the conditions required to obtain smooth surface morphologies. Using the results, surfaces were etched with a root-mean-squared (RMS) surface roughness of 1.7 nm. Furthermore, the etch selectivity is used to gain access to buried p-type layers allowing n-p diodes to be fabricated. Contact resistances to the exposed p-type layers were found to be superior to those obtained by dry etching.
KeywordsGaN wet etching dry etching
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The material used in this work was grown using an EPSRC grant through the National Centre for III-V Technologies at Sheffield University. One of the authors (RTG) also acknowledges funding of a studentship from the EPSRC.
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