Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 24: Photonic crystals II
HL 24.11: Vortrag
Dienstag, 26. Februar 2008, 12:15–12:30, EW 202
Ethanol gas sensor based on Silicon Photonic Crystal — •Stefan L. Schweizer1, Jürgen Wöllenstein2, Armin Lambrecht2, and Ralf B. Wehrspohn1 — 1Institut für Physik, Universität Halle-Wittenberg, 06099 Halle — 2Fraunhofer Institut Physikalische Messtechnik, Heidenhofstr. 8, 79110 Freiburg
Gas sensors based on optical absorption are advantegous because of their sensitivity, selectivity and dynamic range. We use a 2D Photonic Crystal (PhC) based on silicon for qualitative and quantitative gas analysis of ethanol. The bandstructure of PhCs offers intriguing possibilities for the manipulation of electromagnetic waves. Taking advantage of the low group velocity and certain mode distributions for some k-points in the bandstructure of a PhC should enable the realization of very compact sensor devices for mobile applications.
We prepared sensing elements based on macroporous silicon PhCs consisting of up to 1000 of pore rows and measured the transmission with and without gas through the porous sensing element. We observed an enhancement in sensitivity of about 3 to 4 compared to a gas cell without a PhC. For further increase of the enhancement factor we optimized the photoelectrochemical etch process and switched to neutron transmutated doped silicon. Simulations predict an enhancement factor of about 30 which would allow a reduction of the setup by this factor - without loss of performance!