GaAsN interband transitions involving localized and extended states probedby resonant Raman scattering and spectroscopic ellipsometry

Interband transitions in GaAs1-xNx (0 less than or equal tox less than or e qual to0.033), involving a localized resonant N-derived energy level and th e GaAs-like L conduction and valence band states, have been studied by reso nant Raman scattering and spectroscopic ellipsometry, respectively. Raman s cattering by the GaN-like LO2 phonon showed for x approximate to0.01 a pron ounced resonant enhancement for incident photon energies approaching the mo stly N-related E+ transition at around 1.8 eV, but not at the E-1 and E-1+D elta (1) interband transitions, reflecting the strongly localized nature of both the N-related electronic level and the Ga-N vibrational mode. Spectro scopic ellipsometry, in contrast, being sensitive to the overall dielectric function of the GaAsN, revealed the effect of N incorporation on the GaAs- like E-1 and E-1+Delta (1) interband transitions, which is a high-energy sh ift with increasing N-content accompanied by a significant broadening. (C) 2000 American Institute of Physics. [S0003-6951(00)04148-6].