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×${10}^{17}$ and 4×${10}^{19}$ ${\mathrm{cm}}^{-3\mathrm{}}$ were studied at temperatures between 5 and 80 °K using both 5145- and 4880-Å 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 ${\alpha }_{\mathrm{ij}}\ne 0$ only for $i\ne j$ and $\hat{j}\parallel \hat{H}$. 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.