Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 11: Carbon: Nanotubes, Diamond and Silicon Carbid

HL 11.4: Vortrag

Montag, 26. März 2012, 12:30–12:45, EW 203

Towards a quantum point contact on hydrogen-terminated single-crystalline diamond — •Moritz Hauf, Patrick Simon, Max Seifert, Markus Stallhofer, Martin Stutzmann, Alexander Holleitner, and Jose A. Garrido — Walter Schottky Institut and Zentrum für Nanotechnologie und Nanomaterialien, Am Coulombwall 4, 85748 Garching

The two-dimensional hole gas which forms at the surface of hydrogen-terminated diamond has already been used for the fabrication of in-plane gated field effect transistors in the past. Until now, no quantum effects have been observed in these structures. However, the two-dimensional nature of the hole gas offers a good starting point for the fabrication of lower-dimensional structures, similar to GaN/AlGaN heterostructures.

In this work we use e-beam lithography to selectively oxidize the H-terminated diamond surface in order to create conductive channels with nano-scale dimensions. We show Coulomb-blockade on surface-conductive channels with a width of 100nm. Furthermore, in-plane gate structures are used to approach conductance quantization in this material system at temperatures below 4K. Varying the gate voltage, we observe stepwise changes of the conductance in channels with widths of 100nm, 150nm, 200nm, and a length of 100nm. We discuss the origin of the conductance quantization in terms of the dimensionality of the hole-gas and possible Coulomb blockade effects at the surface of H-terminated diamond.