Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 50: Poster II

HL 50.52: Poster

Donnerstag, 30. März 2006, 16:30–19:00, P3

Microresonators based on SOI for optical bio-sensory applications — •Dominic Dorfner, Felix Hofbauer, Andreas Kress, Marc Tornow, Jon Finley, and Gerhard Abstreiter — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany

We are investigating the potential to develop photonic biosensors that will combine high spatial resolution and detectivity. Our concept is based on probing the modification of the linear optical response of photonic crystal (PC) defect resonators upon surface bio-functionalization. PCs are fabricated from the biocompatible Silicon-on-insulator (SOI) materials system using electron beam lithography and reactive ion etching. They consist of a hexagonal lattice of air holes perforating the SOI membrane into which cavities are formed by single missing hole defects. Calculations demonstrate that the cavity mode frequency should be very strongly influenced by local changes of refractive index (n) on the surface of the PC. By simulating the attachment of bio-molecules to the surface, a ~8% absolute shift of the mode frequency is predicted as n increases from ~1.3 to ~1.5. For a PC with lattice constant a=340nm (photonic bandgap ~1.2 - 1.4 mu) this would correspond to delta~30nm, easily visible even with rather low cavity Q-factors of one thousand. First optical characterizations were performed using micro-photoluminescence spectroscopy on structures infilled with PbSb nanocrystals. These measurements reveal peaks due to filtering of the QD emission through the cavity mode spectrum, with Q~100.