Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 18: Carbon: Diamond, nanotubes and Buckyballs

HL 18.2: Talk

Monday, March 31, 2014, 15:15–15:30, POT 112

Low dimensional effects in surface conductive diamond — •Patrick Simon, Moritz V. Hauf, Max Seifert, Alexander W. Holleitner, Martin Stutzmann, and Jose A. Garrido — Walter Schottky Institut and Zentrum für Nanotechnologie und Nanomaterialien, Am Coulombwall 4, 85748 Garching

Hydrogen-terminated diamond exhibits a high surface conductivity in air. While theoretical models have suggested that a two-dimensional hole gas is formed shortly beneath the surface, no experimental proof has been reported yet.

In this work, we prove the low dimensional character of the surface conductive channel of hydrogen-terminated diamond. Using e-beam lithography and an oxygen plasma process we selectively oxidize the hydrogen-terminated diamond surface in order to fabricate in-plane gated field effect transistors. We demonstrate the lateral depletion of the conductive channel of devices with widths of up to 250 nm by applying a gate voltage. At liquid helium temperatures we observe a transition from the initial 2D system to a 1D system exhibiting quantized conductance. In a bias regime where the channel is almost fully closed, we observe Coulomb blockade effects characteristic of multiple islands that vary in size with the applied bias. The islands dimension exhibits a gate voltage dependence which is a direct result of the two-dimensional nature of the hole gas formed by the hydrogen-terminated surface.