Photoemission Study of the Electronic Structure of ZnTe

We report the results of ZnTe photoemission studies over a range in photon energy extending from 6.0 to 11.6 eV. Single crystals were cleaved and studied at pressures less than ${10}^{-9\mathrm{}}$ Torr. The energy distributions of the photoemitted electrons are rich in structure, and contain as many as six distinct peaks in the electron-energy distribution at a single photon energy. By studying the motion and changes in strength of this structure as the exciting photon energy is varied, we demonstrate that all of it is due to direct transitions. By comparing the experimental data with recent pseudopotential and orthogonalized-plane-wave calculations, we determine the energies of many states over a range extending from 4 eV below to about 10 eV above the top of the valence band. Transitions are assigned primarily to $\Gamma$, $X$, and $L$ and along $\Sigma$, $\Delta$, and $\Lambda$ on the basis of the one-electron band structure. Experimental values for energy states are generally within a few tenths of an eV of theory, particularly for valence bands, although there may be a discrepancy at the conduction-band level $L_3$.