Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 61: Poster II: Materials, Interfaces and Heterostructures
HL 61.38: Poster
Donnerstag, 25. März 2010, 18:00–20:00, Poster D1
Cross-Section Scanning Tunneling Spectroscopy on a resonant-tunneling diode structure — Karen Teichmann1, Martin Wenderoth1, •Sergej Burbach1, Rainer G. Ulbrich1, Klaus Pierz2, and Hans W. Schumacher2 — 1IV. Physikalisches Institut, Georg-August Universität Göttingen — 2Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig
We investigated a resonant-tunneling diode structure by Cross-Sectional Scanning Tunneling Microscopy (STM) and Spectroscopy. The diode structure was grown by molecular-beam epitaxy on a n+-doped GaAs (100) substrate and consists of self-assembled InAs quantum dots embedded in AlAs barriers (both 4 nm) each followed by undoped GaAs prelayers (15 nm) [1]. We use a low temperature STM working under UHV conditions at 5 K. The samples are cleaved in UHV to obtain a clean and atomically flat surface perpendicular to the diode-structure. Atomically resolved constant current topography images taken simultaneously at different bias voltages, (both positive and negative voltage) show the high quality of the heterostructure. Local I(V)-spectroscopy resolves the band edge alignment across the heterostructure. On negative bias voltage several peaks in the differential conductivity are observed. The voltage position of these peaks varies with distance from the interface. We attribute the origin of the enhanced differential conductivity peak to an interaction between the potential induced by the tip and the quantum dot layer. We acknowledge financial support by the DFG SPP 1285.
[1] I. Hapke-Wurst, et al., App. Phys. Lett. 82, 1209 (2003)