Edge Emission and Magneto-Optical Effects in CdSe

Abstract

More than a score of sharp, narrow, spectral lines (half-widths ∼0.5 Å) have been observed in the edgeemission spectra of CdSe platelets. Several typical lines have been examined in detail at temperatures ∼1°K. The spectral-line splittings of singlets, as well as zero-field-split doublets, have been studied in magnetic fields up to 45 000 G. The splitting of $I_7$ (an emission line appearing at 6827.43 Å) has been studied as a function of magnetic field strength. In accordance with the Thomas-Hopfield theory, arguments are presented for the association of $I_7$ with a bound-exciton complex; this line is observed to split linearly as a function of magnetic field strength and isotropically as a function of crystal orientation. Isotropic electron and hole $g$ values have been determined for $I_7:g_e=0.50\mathrm{}$ and $g_h=1.96\mathrm{}$. A complex multiplet, $I_{9a}-I_{9b}$ (6855.14, 6857.35 Å), whose components split linearly and isotropically, has also been studied as a function of field strength. It is shown how the components of $I_{9a}-I_{9b}$ could arise from the excited states of a neutral exciton complex. Isotropic splittings were observed for all of the bound exciton lines; also, the electron $g$ values were observed to be isotropic and essentially the same for all lines (about 0.50). Unlike CdS and ZnO, orientation-dependent Zeeman patterns were not observed in the CdSe spectra.