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HL: Halbleiterphysik

HL 43: Symposium Nitride

HL 43.2: Vortrag

Donnerstag, 27. März 2003, 15:00–15:30, POT/81

The Role of Oxides for III-Nitride Sensors — •Martin Stutzmann, Martin Eickhoff, Georg Steinhoff, Martin Hermann, and Olaf Weidemann — Walter Schottky Institut, Technische Universitaet Muenchen, 85748 Garching, Germany

Epitaxial layers of GaN and AlGaN/GaN heterostructures can be used for a large variety of sensor structures.In the past couple of years, we have systematically investigated the response of such layers to mechanical, optical, ionic, and chemical signals, with quite promising results which will be reviewed briefly. The unique combination of their well-known optoelectronic properties together with their thermal and chemical stability would make III-nitrides a very promising material system for multidimensional sensor devices, indeed.

In this talk, we present recent results concerning the role of surface oxides on GaN and AlGaN for the detection of oxidising or reducing gases using Pt/GaN or Pd/GaN Schottky diodes, and for the detection of ions in an electrolyte with the help of GaN/AlGaN high electron mobility transistors. The formation of a natural oxide was measured by in-situ XPS studies. In addition, anodic and thermal oxidation has been investigated.Our results indicate that the surface oxide rather than the free nitride surface is responsible for the sensitivity of III-nitrides upon exposure to gases or ions. In addition, we will discuss the potential of III-nitrides for future biosensor applications .