Wet etching photoenhanced

Youtsey C, Adesida I, Romano L and Bulman G, Smooth photoenhanced wet etching of n-type GaN Appl. Phys. Lett 72 560-2... 

To date, no photoenhanced wet etching technique has been reported for p-type GaN. The difficulty in photo-etching p-type semiconductors arises from the nature of the surface depletion region exhibited by p-type materials [30], The depletion of holes from p-type surfaces due to surface states results in a near-surface electric field, which sweeps photogenerated holes away from the surface into the bulk. A variety of techniques have been utilised to electrochemically etch other p-type semiconductors, including the application of biases to supply holes from the p-type bulk and the use of reductive etch chemistries, but these remain to be demonstrated for p-GaN. 

C. Youtsey, I. Adesida, L. T. Romano, and G. Bulman, Smooth n-type GaN surfaces by photoenhanced wet etching, Appl. Phys. Lett. 72, 560-562 (1998). 

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