Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 16: GaN: Bauelemente
HL 16.7: Vortrag
Dienstag, 9. März 2004, 11:45–12:00, H13
AlGaN/GaN Field Effect Transistors for Chemical and Biological Sensor Applications — •Georg Steinhoff, Barbara Baur, Martin Hermann, Martin Stutzmann, and Martin Eickhoff — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching
Field effect transistors based on AlGaN/GaN heterostructures are of great interest for chemical and biochemical sensor applications. The electrical properties of the polarization induced 2DEG, which is formed at the AlGaN/GaN heterointerface are highly sensitive to changes in the surface potential. Additionally, the device surface is chemically inert in aqueous solutions and non-toxic to living cells. We have studied the response of nonmetallized gate regions of AlGaN/GaN transistors and transistor arrays to changes in the concentration of specific ions in the ambient electrolyte. The potential drop at the interface between the gate surface and the electrolyte solution was measured and used as a sensor signal. A linear sensor response of approximately 55 mV/pH was found for variations in the H+-concentration between 10-1 and 10-13 mol/l, which is close to the theoretical Nernst limit, determined by the native oxide layer present on the surface. Sensitivity towards Na+, K+, Ca2+ and Cl–-ions and long term stability of the transistor devices in aqueous solutions were also investigated. As a first biophysical application of these sensors we discuss the detection and analysis of ionic signals of cells cultivated directly on the device surface.