Raman Spectroscopy of Wurtzite InN Films Grown on Si

Abstract

We have used Raman spectroscopy to study indium nitride thin films grown by molecular beam epitaxy on (111) silicon substrates at temperatures between 450 and 550°C. The Raman spectra show well defined peaks at 443, 475, 491 and 591 cm$^{-1}$, which correspond to the $A_1$(TO), $E_1$(TO), $E_2^\textrm{high}$, and $A_1$(LO) phonons of the wurtzite structure, respectively. In backscattering normal to the surface the $A_1$(TO) and $E_1$(TO) peaks are very weak, indicating that the films grow along the hexagonal $c$-axis. For a growth temperature of 500°C, the $E_2^\textrm{high}$ peak has a full width at half maximum of 7 cm$^{-1}$, which is comparable to the value reported for wurtzite InN films grown on sapphire.