Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 15: Elektronische Struktur III

O 15.3: Vortrag

Dienstag, 25. März 2003, 11:45–12:00, HSZ/02

Quasiparticle Electronic Structure and Energetics of Point Defects on Semiconductor Surfaces — •Arno Schindlmayr, Magnus Hedström, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4–6, 14195 Berlin-Dahlem

Point defects strongly influence the transport, electronic, and optical properties of semiconductors. In particular, they act as compensation centers and are responsible for Fermi-level pinning. The energetics of transitions between different charge states is hence an important material characteristic. The relevant charge-transition levels contain two energy contributions due to the transfer of an electron from the Fermi level to the defect state and due to the lattice relaxation. While the latter is accessible in density-functional theory (DFT), the underestimation of the band gap translates into a significant error in the first, dominant term. We therefore use the GW approximation for the electronic self-energy to calculate accurate quasiparticle energies within the pseudopotential approach. As specific examples we consider anion vacancies on the GaAs(110) and InP(110) surfaces. Concomitant with the opening of the band gap, the charge-transition levels are raised in comparison to DFT-LDA predictions and show improved agreement with the available experimental data.