Nanoporous InN Films Synthesized using Photoelectrochemical (PEC) Wet Etching

In this study, we have investigated the structural characteristics of nanoporous InN prepared by photoelectrochemical (PEC) wet etching. The PEC process which uses various 0.2, 0.5 and 1.0 wt% aqueous potassium hydroxide (KOH) solution utilizes photogenerated electron-hole pairs to enhance oxidation and reduction reactions taking place in an electrochemical cell. For etching condition using 0.2 wt% KOH solution (sample B), surface became relatively rough, however no pore was found. SEM images show that average pore size for sample C (0.5 wt% KOH solution) and sample D (1.0 wt% KOH solution) was around 30 to 60 nm. However, from our analysis of porous InN prepared by varying the etching condition, the non uniform etch rate across the sample surface is limited by diffusion processes. From the X-ray diffraction scan, porous samples show a broadening of the full width at half maximum with respect to the as-grown InN epilayer. On the other hand, the peak shift for InN (0002) and GaN (0002) diffraction planes was inconsistent. This can be explained by the relatively smaller statistical size distribution of the pores.