0000000000740129
AUTHOR
P. H. Jefferson
Valence-band electronic structure of CdO, ZnO, and MgO from x-ray photoemission spectroscopy and quasi-particle-corrected density-functional theory calculations
The valence-band density of states of single-crystalline rock-salt CdO(001), wurtzite $c$-plane ZnO, and rock- salt MgO(001) are investigated by high-resolution x-ray photoemission spectroscopy. A classic two-peak structure is observed in the VB-DOS due to the anion $2p$-dominated valence bands. Good agreement is found between the experimental results and quasi-particle-corrected density-functional theory calculations. Occupied shallow semicore $d$ levels are observed in CdO and ZnO. While these exhibit similar spectral features to the calculations, they occur at slightly higher binding energies, determined as 8.8 eV and 7.3 eV below the valence band maximum in CdO and ZnO, respectively. Th…
Unification of the electrical behavior of defects, impurities, and surface states in semiconductors: Virtual gap states in CdO
In contrast to conventional semiconductors, native defects, hydrogen impurities, and surface states are all found to be donors in $n$-type CdO. Using this as a model system, the electrical behaviors of defects, dopants, and surface states in semiconductors are unified by a single energy level, the charge neutrality level, giving much insight into current materials and allowing a band-structure engineering scheme for obtaining desired custom electronic properties in new compound semiconductors.
Ab-Initio Studies of Electronic and Spectroscopic Properties of MgO, ZnO and CdO
We present ab-initio calculations of excited-state properties within single-particle and two-particle approaches in comparison with corresponding experimental results. For the theoretical treatment of the electronic structure, we compute eigenvalues and eigenfunctions by using a spatially nonlocal exchange-correlation potential. From this starting point, quasiparticle energies within the fully frequency-dependent G(0)W(0) approximation are obtained. By solving the Bethe-Salpeter equation, we evaluate optical properties, including the electron-hole attraction and the local-field effects. The results are compared with experimental spectra from soft X-ray emission, as well as from X-ray photoe…
X-ray photoemission studies of the electronic structure of single-crystalline CdO(100)
The electronic structure of single-crystalline CdO is investigated using X-ray photoemission spectroscopy. The surface is prepared by in situ Ar+ ion bombardment and annealing (IBA). The core level spectra before and after the IBA are presented, and reveal a dramatic reduction in the surface contamination. The semi-core Cd 4d level and valence band region following the IBA are also shown. The surface Fermi level is pinned 1.3 +/- 0.10 eV above the valence band maximum. (c) 2007 Elsevier Ltd. All rights reserved.