Raman Scattering Signature of a Localized-to-Delocalized Transition at the Inception of a Dilute Abnormal GaAs_(1-x)N_x Alloy

摘要

We identify the signature of a localized-to-delocalized transition in the resonant Raman scattering spectra from GaAs_(1-x)N_x. Our measurements in the ultradilute nitrogen doping concentrations demonstrate an energy shift in the line width resonance of the LO phonon. With decreasing nitrogen concentration, the E_W line width resonance energy reduces abruptly by ca. 47 meV at x ≈ 0.35%. This value corresponds to the concentration at which GaAs_(1-x)N_x has been recently shown to transition from an impurity regime to an alloy regime. Our study elucidates the evolution of dilute abnormal alloys and their Raman response.