CRITICAL TEST OF CDTE(100) ANGLE-RESOLVED PHOTOEMISSION SPECTRA WITH BAND-STRUCTURE CALCULATIONS

Angle-resolved synchrotron-radiation photoemission spectroscopy was used to determine the spin-orbit splitting between the GAMMA-8 and GAMMA-7 valence bands and to map the dispersion E(k) of the light- and heavy-hole bands as well as the split-off valence band along the [100] direction in CdTe. At a photon energy of hv = 10 eV, we find that a direct transition from the Brillouin-zone center is possible only from the highest occupied GAMMA-8 valence band, while for hv = 11 eV, the split-off GAMMA-7 band has comparable transition probability and also contributes to the normal-emission spectrum. The measured spin-orbit splitting DELTA-epsilon-s.o. = 0.95 eV is in agreement with values reported from optical measurements. The experimentally determined valence-band critical-point energies are X7 less-than-or-equal-to -1.4 eV, X6 = -2.2 eV, and X7 = -4.4 eV. A comparison of these data points well as the dispersion behavior of the top three valence bands is made with results based upon nonlocal pseudopotential, tight-binding, and self-consistent local-density approximations.