Analysis and characterization of GaN nanostructure by electrochemical etching

Abstract

Nanostructured GaN layers have been fabricated by electrochemical and laser-induced etching (LIE) processes based on n-type GaN thin films grown on the Si (111) substrate with AlN buffer layers. The effect of varying current and laser power density on the morphology of the GaN layers is investigated. The etched samples exhibited a dramatic increase in photoluminescence intensity as compared to the as grown samples. The average diameter of the GaN crystallites was about 7–10 nm, as determined from the PL data The Raman spectra also displayed stronger intensity peaks, which were shifted and broadened as a function of etching parameters. A strong band at 522 cm−1 is from the Si (111) substrate, and a small band at 301 cm−1, due to the acoustic phonons of Si. Two Raman active optical phonons are assigned h-GaN at 139 cm−1 and 568 cm−1due to E2 (low) and E2 (high) respectively.