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HL: Halbleiterphysik

HL 12: Poster I

HL 12.35: Poster

Montag, 8. März 2004, 16:30–19:00, Poster A

Gas Sensors Based on 2D Photonic Crystals — •Torsten M. Geppert¹, Stefan L. Schweizer², Ralf. B. Wehrspohn², and Armin Lambrecht³ — ¹Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany — ²Universität Paderborn, Dept. Physik, Warburger Str. 100, 33098 Paderborn, Germany — ³Fraunhofer-Institut für Physikalische Messtechnik, Heidenhofstr. 8, 79110 Freiburg, Germany

We investigate a new kind of gas sensor devices utilizing 2D photonic crystals (PhCs) made up of straight air pores electrochemically etched into Si wafers. Based on the reduction of the group velocity of light in a PhC the interaction time between gas and light should be drastically increased allowing to minimize the size of the gas sensing device as compared to currently used gas sensor systems. To achieve this miniaturization, three requirements have to be met by the PhC. First, the photonic bandstructure should have only a very small slope for the frequency of interest to achieve a low group velocity. Second, the electric field has to be concentrated in the pores to allow interaction between the light and the gas. Third, the symmetry of the field distribution in the PhC has to allow the coupling of the incoming light to the photonic bandstructure. Unfortunately, due to the low group velocity, the reflection at the interface air-photonic crystal is very high resulting in a low coupling efficiency. This shortcoming could be circumvented by the use of appropriate tapers. In our study we investigate several geometries of the photonic crystal lattice and taper concepts to allow the use of 2D PhCs as gas sensor devices.