Rare earth implanted Si-based light emitters and their use for smart biosensor applications

In this presentation we will review our recent progresses in the development of Si-based light emitters consisting of a MOS structure with a rare earth implanted SiO2 layer. Depending on the implanted element, namely Gd, Tb and Eu, the devices exhibit strong electroluminescence in the UV, the green and in the red spectral region. It will be shown that the implantation and annealing conditions during the fabrication strongly influence the microstructural, electrical and electro¬luminescence device properties and are of special importance for the efficiency and life time of future devices. In order to improve the stability of the devices, both LOCOS (local oxidation of Si) processing and additional protection layers made of SiON were applied to the devices. The advantages and the shortcomings of these light emitters regarding their efficiency, life time, electrical excitation conditions, cut-off frequencies and miniaturization potential are compared with the needs of smart photonic and biosensor applications. A special approach for utilizing the light emitters for the detection of organic pollutants in fluid media by fluorescence analysis is discussed in more detail. In this approach the light emitter is directly placed beneath the dye-labelled sample exciting the dye whose light emission can be recorded by a suitable external detector.