Photoemission spectroscopy using synchrotron radiation. I. Overviews of valence-band structure for Ge, GaAs, GaP, InSb, ZnSe, CdTe, and Agl

Abstract

We determine bandwidths and critical-point positions with respect to the valence-band edge for the valence bands of several extensively studied semiconductors (with an accuracy of about 0.3 eV) by using photoemission densities of states derived from photoemission specti'a obtained in the 24-78-eV photon energy range. These photoemission spectra were obtained using synchrotron radiation from an electron storage ring; a double-pass, cylindrical, electrostatic, electron energy analyzer; and samples cleaved and measured in situ in ultrahigh vacuum. We give a detailed description of the data-reduction techniques by which electronic state densities and certain valence-band feature positions are determined from photoemission spectra. This description includes a discussion of the effect of various phenomena such as optical-transition-probability variations and Auger-emission peaks. Tables are presented which compare our valence-band-position values with the results of both empirical calculations fit to optical data as well as ab initio calculations. We find systematic and significant differences between experiment and calculations fit only to optical data, these differences increasing with crystal ionicity, while ab initio calculations generally give a better fit to experiment.

The influence of lattice oxygen on the initial growth behavior of heteroepitaxial Ge layers on single crystalline PrO2(111)∕Si(111) support systems

“…The spectrum is in agreement with He I UPS data on Ge͑111͒ surfaces reported in the literature. 35,53 The wide band from 0 to 5 eV shows the contribution of Ge 4p states to the VB and the peak at 7.7 eV is the result of hybridized Ge 4p -4s states. The pure Ge 4s band, expected at around 10 eV from theoretical DOS calculations, is not visible, due to the fact that the He I ionization cross section for these states is by two orders of magnitude lower than for Ge 4p electrons.…”

Empirical pseudopotential calculations of Cd1−xMnxTe

“…12 This discrepancy could have arisen from the experimental data used in the present work. [16][17][18] Such data were not available to Cohen and Bergstresser and are indeed inconsistent with their band structure. Furthermore, the lattice constant and the number of plane waves used in the present calculations are also different.…”

Imaging interatomic electron current in crystals with ultrafast resonant x-ray scattering

“…The sp 3 -hybridized electrons form two outermost valence bands of germanium with a maximum energy splitting of 4.5 eV [47]. The wave functions φ 1(2),i of the hybrid orbitals are a linear combination of one s and three p orbitals of each Ge atom, which we denote as φ s , φ p x , φ p y , and φ p z , respectively.…”