N-induced vibrational modes in GaAsN and GaInAsN studied by resonant Raman scattering

Abstract

Vibrational modes introduced by the incorporation of N into GaAs and GaInAs have been studied by Raman spectroscopy on samples grown by molecular-beam epitaxy using a rf nitrogen plasma source. When proceeding from GaAs1−xNx to Ga1−yInyAs1−xNx with x⩽0.04 and y⩽0.12, the nitrogen-induced vibrational mode near 470 cm−1 observed in GaAsN was found to broaden and to split into up to three components with one component at a frequency higher than that of the Ga–N mode in GaAsN. This observation shows that the incorporation of In into GaAsN strongly affects the local bonding of the N atoms by changing the local strain distributions as well as the formation of a significant fraction of In–N bonds. The resonant enhancement in the scattering cross section of the Ga–N vibrational mode, observed in low N-content GaAs1−xNx (x≈0.01) for incident photon energies matching the mostly N-related E+ transition at around 1.8 eV, was found to broaden significantly upon increasing N content as well as upon the addition of In to form GaInAsN.