Raman Characterization of Gallium Nitride Nanowires Deposited by Chemical Vapor Deposition

摘要

Gallium Nitride Nanowires (GaN-NWs) were synthesized on p-type c-Si (100) by thermal chemical vapor deposition (CVD) using Ag, Fe, In, Ni as catalysts. These NWs were synthesized with variation of H_2 flow rate from 40 to 120 standard cubic per centimeter (sccm) while maintaining constant flow of N_2 gas at 120 sccm. FESEM, rTIK, Raman and photoluminescence spectroscopy were used to characterize the GaN-NWs for microstructure, vibrational and optical properties. The microstructure of GaN-NWs reveals thin and hairy nanowires for Ag and In catalysts while long and thick NWs were observed for Fe and Ni catalyst. Raman spectra reveal that the peak position of A_1(LO), A-1(TO) phonon shifted to higher frequency from 705.37 to 716.58 and 520.94 to 528.71 cm~(-1), whereas E_1(TO) phonon shows pronounced red shift from 544.36 to 540.60 cm-1. In a similar sideline, fwhm of A_1(LO), A_1(TO) phonon increases from 13.11 to 21.01 cm~(-1) and 16.99 to 20.78 cm~(-1), whereas fwhm decreases for E_1(LO) and E_1(TO) phonon. We have found Surface Optic (SO) phonon of GaN-NWs at 610 cm~(-1) in FTIR spectra. Room temperature photoluminescence (PL) spectra show a prominent blue luminescence from GaN-NWs.