Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.32: Poster

Thursday, March 26, 2009, 15:00–17:30, P2

Electronic transport at the interface between diamond and aqueous electrolyte — Markus Dankerl, Eberhard Ulrich Stützel, •Andreas Lippert, Martin Stutzmann, and Jose Antonio Garrido — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching.

Undoped single crystalline diamond with a hydrogen-terminated surface shows a p-type surface conductivity. This surface conductivity is based on a two-dimensional hole channel formed by the band bending beneath the surface. It is not only stable in electrolyte but can also be modulated by an applied potential through the electrolyte, enabling the design of solution gate field effect transistors (SGFETs). Owing to the remarkable stability and biocompatibility of diamond, SGFETs based on diamond are highly interesting for biosensing and medical applications. We have investigated the surface conductivity of hydrogen-terminated single crystalline diamond using in-liquid Hall effect measurements under potential control. Thus, we were able to independently determine the carrier concentration and the carrier mobility. We observe that the mobility shows different variations with the carrier concentration at different levels of the carrier concentration. We discuss this in the context of localization and scattering mechanisms e.g. surface scattering. Studies on the effect of temperature on the mobility reveal no activated behavior beyond the influence of the carrier concentration. The effect of temperature on the concentration of carriers itself fits the concept of an interfacial capacitance at the diamond/electrolyte interface.