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HL: Halbleiterphysik
HL 17: Poster Ib
HL 17.61: Poster
Freitag, 4. März 2005, 16:30–19:00, Poster TU F
Scanning Tunneling Spectroscopy of Carbon and Zinc Acceptors in GaAs — •S. Loth1, M. Wenderoth1, T. C. G. Reusch1, L. Winking1, R. G. Ulbrich1, S. Malzer2, and G. Döhler2 — 1IV. Physikalisches Institut, Universität Göttingen, D-37077 Göttingen — 2Institut für Technische Physik, Universität Erlangen-Nürnberg, D-91058 Erlangen
Carbon and zinc dopants embedded near in-situ cleaved {110} surfaces of GaAs were studied with low temperature UHV scanning tunneling spectroscopy (STS) at 8K. Both dopants are shallow substitutional acceptors, carbon on an As site and zinc on a Ga site. Laterally resolved STS measurements show conductivity at voltages well below 1V, localized at the dopant atoms. In the voltage interval from 0V to 1V the conductance above undisturbed surface regions vanishes. We employ a quantum-mechanical transport simulation to describe the tunnel current along a path perpendicular to the sample surface from the metallic tip to the bulk of the semiconductor. The comparison of the simulated spectra with the measured ones allows us to identify the transport mechanisms which contribute to the specific shape of the I(V) characteristics.