Experimental self-energy corrections for various semiconductors determined by electron spectroscopy

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Abstract
This paper determines the energy dependence of experimental self-energy corrections, Δ(E), for local-density-functional-theory eigenvalues due to many-body interactions in Si, Ge, GaAs, and ZnSe. The self-energy corrections are determined by comparing shifts between the theoretical local-density approximation and experimental densities of state obtained with use of x-ray photoemission and bremsstrahlung isochromat spectroscopy (inverse photoemission). Δ(E) is nominally independent of energy in the conduction band for these semiconductors but exhibits a distinct energy dependence within the valence band. The results compare well with recent quasiparticle calculations in general, although the observed energy dependence is not predicted by theory in the case of Ge. The self-energy corrections are strongly dependent on the localization of the state. Many-body effects due to plasmon effects are also investigated with use of core-level data. The inelastic background due to electron-hole pair production is roughly a factor of 10 lower for inverse photoemission compared with photoemission; a result which suggests that some many-body effects may be intrinsic. Intriguing conduction-band results for states up to 600 eV above the Fermi level are presented.