Structural and optical characteristics of porous InAlGaN prepared by photoelectrochemical etching

The effect of etching duration on the porous structure of quaternary III-nitride alloy, InAlGaN prepared using the photoelectrochemical etching technique was evaluated in this study. Field emission scanning electron microscopy (FE-SEM) revealed that the pore density of the sample increased with increased etching duration, as did the root mean square (RMS) roughness, as measured by atomic force microscopy (AFM). The high resolution X-ray diffraction (HR-XRD) rocking curve measurement showed that dislocation density was reduced in samples etched for 15 and 20 min. In the Raman spectra, the InGaN-like E-2(high) phonon mode of porous InAlGaN samples exhibited red shift characteristic relative to the non-porous sample due to relaxation of compressive stress of the porous sample. These results illustrate that etching duration affects the structural and optical properties of the InAlGaN sample. (C) 2014 Elsevier B.V. All rights reserved.