Nanoporous InGaN prepared by KOH electrochemical etching with different light sources

Abstract

A number of porous InGaN samples of relatively high In composition ∼47% were prepared via electrochemical etching using diluted KOH bath. The porous samples were synthesised with the assistance of different types of illumination; Xenon and UV light. Fabrication of porous InGaN without light illumination was also demonstrated. The effects of using different light sources on the properties of porous InGaN were studied for the first time. Observation through field emission scanning electron spectroscopy (FESEM) revealed that different types of illumination resulted in different surface morphologies. Overall, the high resolution X-ray diffraction (HR-XRD) rocking curves measurement showed that the value of full width at half maximum (FWHM) of all etched samples decreased relative to the as-grown sample due to removal of dislocation defects on the surface after etching. It should be noted that, etched sample that used Xenon illumination showed the lowest FWHM value. On the other hand, photoluminescence (PL) measurement indicated that all of the porous InGaN samples exhibited higher PL intensity than the as-grown sample, showing improvement in the aspect of optical property. Moreover, red-shifted characteristic in PL spectra was also observed in the porous samples, suggesting a relaxation of compressive stress occurred in the samples. The properties observed imply the potential utility of porous InGaN in optical and sensor applications.