Electronic Raman Scattering of Photoexcited Electrons in Germanium

抄録

We measured electronic Raman scattering originating from photoexcited L valley electrons in undoped, p-type (N_h=10¹⁷ cm^-3), and n-type (N_e=10¹⁷ cm^-3) germanium crystals at lattice temperature from RT to 76 K when stimulated by 1.58-eV laser light. From analysis of the power dependence of Raman intensity in the three samples and comparison of the spectral shape with reported data onheavily doped n-type crystal, the origin of this scattering is ascribed to electrons in the L valley. We analyzed this Raman scattering by using Ipatova'stheory, and found that phononassisted intervalley scattering was dominant in the temperaturedependence of the width (FWHM of modified Lorentzian) of the electronic Raman scattering spectra.We also succeeded in reproducing the temperature dependence ofscattering intensity taking into account the temperature dependentdiffusion constant of electrons.