Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 46: Hybride Systeme
HL 46.2: Vortrag
Donnerstag, 27. März 2003, 14:45–15:00, BEY/154
Organically passivated GaAs/AlGaAs HEMTs for sensor applications in fluids — •S. Luber1, K. Adlkofer2, U. Rant1, A. Ulman3, M. Grunze4, D. Schuh1, M. Tanaka2, M. Tornow1, and G. Abstreiter1 — 1Walter Schottky Institut, TU München, 85748 Garching — 2Lehrstuhl f. Biophysik - E22, TU München, 85747 Garching — 3Dep. of Chem. Eng. and Chem., Polytec. Univ., NY 11201, USA and Garcia MRSEC — 4Lehrstuhl f. Angew. Phys. Chemie, Univ. Heidelberg, 69120 Heidelberg
Gate-less, laterally patterned planar FETs based on surface near 2DEGs in GaAs/AlGaAs heterostructures are promising candidates for the electrical detection of (bio-) molecules. Obligatory, a functionalization of the semiconductor surface is demanded to passivate the substrate against electrochemical decomposition and allow effective electrostatic coupling of the surface potential to the conductive channel.
In this work we studied the impact of solvent polarity on the electrical conductance of chemically passivated, surface near 2DEG samples which were coated with self-assembled monolayers of mercaptobiphenyls with different functional groups (-H, -CH3, -OH). It was found that polar solvents like methanol or acetone decreased the conductance significantly, while non-polar solvents (e.g. cyclohexane) did not cause a distinct change. We tentatively introduced a qualitative model to interpret the observed resistance change in terms of the molecular dipole moment on the surface.
In our recent experiments, we could also accomplish the increased stability of passivated devices under physiological conditions.