Valence and Conduction Band- Structure of Ge Using Theoretical and Experimental Photoemission Spectra from 6.5 to 23 eV

Abstract

Experimental spectra for Ge obtained using synchrotron radiation (hν ≤ 23 eV) are compared with predictions of a direct-transition theory which includes anisotropic transmission through the (111) cleaved surface. The direct transition-determined structure plot for Ge (peak binding energies as a function of photon energy), as well as other spectral features, are fit well up to hν ≳ 23 eV using a d-nonlocal pseudopotential model. We demonstrate that this model provides a proper description of conduction band topology far (~ 1 Ryd) above the gap. Our ability to obtain these results shows that features predicted by an anisotropic, direct opticaltransition model can determine one-electron energy bands over a wide energy range even in the presence of short escape depths and surface-associated emission.