Microarrays of silicon-based light emitters for novel biosensor and lab-on-a-chip applications

We have demonstrated intense violet electroluminescence (EL) from thermally-grown SiO2 films containing Ge nanocrystals produced by ion beam synthesis. An outline is given of the electrical and optical characteristics of ITO/SiO2/Al light-emitting devices incorporating Ge nanocluster-rich oxide films. Optimization schemes based on the use of local oxidation of Si (LOCOS) have been developed and tested successfully. Arrays of 4 × 6 light-emitting devices with a diameter of 300 μm and spacing of 500 μm between the adjacent devices have been formed using standard lithography patterning. Bioanalyses have been carried out following fluorescent-based detection procedures. As distinct from the standard case of diagnostics in which the light source is typically a laser and the necessary spatial resolution is provided by a CCD camera, our light sources are small enough to immediately ensure high resolution while permitting their light emission to be detected by single inexpensive Si diodes. The relevance of the all-Si light sources to microarray, miniaturized sensor and lab-on-a-chip systems for point-of-care diagnostics is discussed. Finally, first EL spectra of Si-based light sources containing Tb are shown.