Spin-Flip Raman Scattering from Conduction Electrons in CdS and ZnSe

Inelastic light scattering from free-carrier spin-flip excitations has been observed in the wide-band-gap semiconductors CdS and ZnSe in magnetic fields up to 100 kOe. In-doped ZnSe and CdS having carrier concentrations between 5×{}10¹⁷ and 4×{}10¹⁹ cm^-3 were studied at temperatures between 5 and 80 ^∘{}K using both 5145- and 4880-{} excitation from an argon-ion laser. Absolute values of the scattering efficiency are given for all samples. The efficiency is quite high, and for those samples exhibiting narrow spin-flip linewidth the peak scattering efficiencies appear large enough to make stimulated spin-flip Raman scattering feasible. The observed polarization selection rules show αᵢⱼ≠0 only for i≠j and ^j∥^H. The dependence of the Raman-frequency shift upon magnetic field implies effective g values for the conduction electrons of 1.86 and 1.18 for CdS and ZnSe, respectively. Several features of the spectra, including carrier-concentration dependence for the spin-flip cross section and linewidth, are not accounted for by existing theories.