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In the present paper we show results of dark current-voltage measurements performed on p+ a- SiC:H/n c-Si heterojunction diodes at various temperatures (100–400K). We investigated the voltage derivative of these J-V curves in order to the distinguish possible current transport mechanisms. It was found that for low temperatures (<300K), the current is determined by recombination of carriers in the crystalline silicon, whereas at high temperature (>300 K), by a tunnelling mechanism. At room temperature, both mechanisms contribute to the current. By using an equivalent circuit model and detailed numerical simulations we have interpreted our experimental characteristics. The simulations done at room temperature, show that at low forward bias voltage the current is controlled by recombination in the crystalline silicon and that at high forward bias voltage by a combination of multi-step tunnelling and a-SiC:H series resistance. For interface state densities equal to or higher than 1012 cm−2, the recombination was found to be dominated by the states at the amorphous-crystalline silicon interface.

The application field of high power semiconductor lasers is growing rapidly and covers e.g. solid state laser pumping, metal and plastic welding, hard and soft soldering, surface treatment and others. Preferably those applications are attractive, which do not require extremely high beam quality.We have investigated high power diode-laser bars from 808 nm to 980 nm. The scope of this presentation is on focusability and beam quality. For better beam shaping structures with reduced fill factor of 25% to 30% were developed. They were operated in continuous wave operation at power levels of up to 55W. Tests indicate extrapolated lifetimes of more than 100 000 hours at 40W at 980nm cw and about 10 000 hours at 45W -50W at 940nm and 808nm. Monolithicly stacked Nonostacks® were investigated. Operation up to 100°C with excellent lifetimes could be demonstrated.New concepts and applications for low mode number high power diode lasers like tapered laser bars are presented. Examples for various current areas of interest in european research facilities will be given.