Enhancement of Structural and Optical Characteristics of Nanostructured InGaN Using Electrochemical Etching

Abstract

In this work, we used an alternating current electrochemical etching technique to fabricate nanostructured InGaN in potassium hydroxide, which serves as an electrolyte. The effects of different current densities during alternating current electrochemical etching on the morphological and optical characteristics of the nanostructured InGaN samples were investigated. The morphology of the nanostructured InGaN samples was determined by extreme high resolution field emission scanning electron microscopy. The pore size (~38 nm) and estimated porosity (~35%) were highest at 250 mA/cm² current density. Furthermore, the surface roughness and average pore depth of the nanostructured InGaN increased with increasing current density, as revealed by atomic force microscopy. X-ray diffraction data showed a reduction in the full width at half maximum value and dislocation density of the nanostructured InGaN samples. The InGaN-like E₂(high) phonon mode of the nanostructured InGaN sample was shifted to a higher frequency in the Raman spectra relative to that of the untreated sample, indicating that stress relaxation occurs in the nanostructured samples. Raman spectra showed an increase in intensity of the nanostructured InGaN samples showing improvement in optical property. The observed properties illustrate the potential of using nanostructured InGaN application in sensing devices.