Nanoporous InGaN of high In composition prepared by KOH electrochemical etching

The fabrication of porous InGaN of high In composition similar to 47% using UV-assisted electrochemical etching in a diluted solution of KOH is demonstrated for the first time. In this paper, the effect of etching time on the morphology of porous InGaN was investigated using field emission scanning electron microscopy (FE-SEM). Pore size and density were found to increase with increasing etching time. In addition, the etching activity at grain boundaries became significant for longer etching periods in which more defective region at grain boundaries had been etched. The reduction in dislocation density due to the etching process was confirmed by a decreased value of the full width at half maximum (FWHM) from high resolution x-ray diffraction (HR-XRD) rocking curve measurements for all porous samples. Porous samples exhibited red-shift characteristics in photoluminescence (PL) spectra with respect to the as-grown sample due to relaxation of compressive stress. Furthermore, the PL intensity of porous samples showed stronger signals relative to the as-grown sample, which is attributed to both the reduction of dislocation density and multiple light scattering from the crystallite sidewalls. Such properties indicate the potential of porous InGaN for applications in optical and sensor devices. (C) 2013 Elsevier Ltd. All rights reserved.