Resonance effects in Raman scattering by dopant-induced local vibrational modes in III-V semiconductors

Abstract

Resonant Raman scattering work is reported on local vibrational modes (LVM) of Si and Be in highly doped III-V semiconductors, such as GaAs, InAs, and InSb. Raman scattering by the LVM of Si donors on group-III lattice sites is found to be strongly enhanced for incident photon energies matching the E1 band-gap energy of the host semiconductor indicating a rather narrow resonance in the scattering cross section. Raman scattering by LVM produced by acceptors, by contrast, is observed for a much wider range of photon energies, which corresponds to a much broader resonance. Possible explanations for this difference in resonance behavior are discussed including resonant donor energy levels derived from the L-point conduction-band minima. The present observations demonstrate, further, that attention must be paid to the appropriate choice of incident photon energies in order to achieve maximum sensitivity in a LVM Raman experiment.