Growth and Characterization of GaN Nanowires by NiCl2 Assisted Chemical Vapor Deposition

Abstract

Large-scale, high-density GaN nanowires were successfully synthesized on Si(111) substrates by the NiCl2 assisted chemical vapor deposition (CVD) method, and their composition, microstructure, morphology, and optical properties were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), and photoluminescence (PL). The results demonstrate that the nanowires are single-crystal GaN with hexagonal wurtzite structure having the size of 20 to 50 nm in diameter with some nanodroplets on their tips, which reveals that the growth mechanism of GaN nanowires agrees with the vapor-liquid-solid (VLS) process. Two first-order Raman active phonon bands move to low shift and E2 (high) and A1(LO) bands broaden, which is caused by size effect.