Regensburg 2004 – scientific programme
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HL: Halbleiterphysik
HL 33: III-V Halbleiter I
HL 33.2: Talk
Wednesday, March 10, 2004, 18:30–18:45, H14
Electronic properties of Carbon and Zinc acceptors in GaAs studied with Low Temperature Scanning Tunneling Microscopy — •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
The electronic properties of single carbon and zinc acceptors located near {110} surfaces of GaAs were studied with a low temperature UHV Scanning Tunneling Microscope at 8K. Zn is a substitutional acceptor on a Ga site with a covalent radius about 30% larger than the replaced Ga atom. C on the other side is a substitutional acceptor on an As site and contracts the bonds to the adjacent Ga atoms by about 15%. In voltage-dependant constant current topographies (-3V to +4.5V) both dopants show comparable patterns, with a variety of different contrasts. The orientation of the features is clearly linked to the exact orientation of the surface under investigation, i.e. (110) vs. (110). Especially at low voltages the C as well as the Zn acceptor appear as nearly equilateral triangular protrusions extended over several nanometers. At higher voltages the symmetry of the triangle evolves into a prolate shape oriented along (100).
This work was supported by the DFG, SFB 602 TP A7