COMPLETE VALENCE-BAND STRUCTURE OF GE DETERMINED BY PHOTOEMISSION

The valence-band structure along the high-symmetry directions "L, "X, and "KX was studied with synchrotron radiation for a wide photon energy range (10"106 eV). A cylindrically shaped Ge crystal with [11»0] axis was used, which allowed us to record the spectra in normal emission for different orientations. The data were analyzed by applying the model of direct transition into free-electron final-state bands. Due to the wide photon energy range, a complete band scheme along the three directions including critical points was obtained. The data are compared with theoretical results and other measurements. The bands along the "KX direction are reported for the first time to our knowledge. Applying the wide photon energy range, the inner potential V0=-8.8 eV was determined self-consistently using the method suggested by Middelmann et al. [Phys. Rev. B 34, 957 (1986)]. © 1990 The American Physical Society.