Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 42: Interfaces/surfaces

HL 42.2: Talk

Thursday, March 26, 2009, 09:45–10:00, POT 51

Control of Donor Charge States with the Tip of a Scanning Tunnelling Microscope — •K. Teichmann¹, M. Wenderoth¹, S. Loth¹, R. G. Ulbrich¹, J. K. Garlef², A. P. Wijnheijmer², and P. M. Koenraad² — ¹IV. Physikalisches Institut, Georg-August-Universität Göttingen — ²PSN, Eindhoven University of Technology, the Netherlands

The functionality of nanoscale semiconductor devices crucially depends on details of the electrostatic potential landscape on the atomic scale and its microscopic response to external electric fields. We report here an investigation of charge state switching of buried single Si donors in 6 · 10¹⁸ cm⁻³ n-doped GaAs with scanning tunnelling microscopy (STM) under UHV conditions at 5K. The effect of tip induced band bending (TIBB) through the freshly cleaved (110)-surface was used to change the charge state of individual donors from neutral to positively charged and reverse. Scanning tunnelling spectroscopy (STS) revealed a ring like feature around each donor center. The ring radius depends on tip bias voltage [1] . The charge state of each donor in the random arrangement of dopants was in most cases unambiguously fixed by the extension of the tip-induced space charge cloud, which was located under the tip and controlled by the applied voltage. For certain geometric configurations the system showed bi- (or multi-) stable behaviour, this lead to dynamic flickering of the ionization sequence. This work was supported by DFG SFB 602 and DFG SPP 1285.

[1] PRL 101, 076103 (2008)