Resonance Raman scattering in InAs near theE1edge

Abstract

The resonance of several first-order [allowed $\mathrm{TO}\left(\Gamma \right)$, forbidden $\mathrm{LO}\left(\Gamma \right)$] and second-order [$2\mathrm{TA}(\Delta \to K)$, $2\mathrm{TO}(\Delta , \Sigma , \Lambda )$, $2\mathrm{LO}\left(\Gamma \right)$] structures of the Raman spectrum of InAs is investigated around the energy of the $E_1$ critical point. The deformation-potential coupling mechanism explains well the resonances of the $2\mathrm{TA}(\Delta \to K)$ and $2\mathrm{TO}(\Delta , \Sigma , \Lambda )$ whereas those of the $1\mathrm{LO}\left(\Gamma \right)$ and $2\mathrm{LO}\left(\Gamma \right)$ are accounted for by the Fröhlich interaction. Several electron-two-phonon deformation potentials are estimated. The sharp resonances of the $1\mathrm{LO}\left(\Gamma \right)$ and $2\mathrm{LO}\left(\Gamma \right)$ are followed over a wide range of temperatures (10-300 K). The results show clearly that the "Raman gap" differs from the optical one. It depends upon the phonons involved in contrast to its temperature dependence. This variation (- 5.0±0.4) × ${10}^{-4\mathrm{}}$ eV ${\mathrm{K}}^{-1\mathrm{}}$ agrees with that of the optical gap.