Dilute (In,Ga)(As,N) thin films grown by molecular beam epitaxy on (100) and non-(100) GaAs substrates: a Raman-scattering study

摘要

We use Raman scattering to investigate a series of In_xGa_(1-z)As_(1-y)N_y epilayers (x ～ 20% and y ～ 3%) coherently grown on (100) and on (N11) GaAs substrates (N - 1, 3, 4, and 5). We use biaxial-strain theory to evaluate the effect of N alloying on the frequency of the GaAs-like phonon optical modes of dilute InGaAsN. We find that N alloying reduces the TO-LO splitting of the GaAs-like modes. We investigate the effect of substrate orientation on the N-related vibrational modes. Our results suggest that the growth direction does not affect substantially the local bonding of N atoms in InGaAsN.