CdS-Si wide-band-gap emitter transistors

Experimental wide-band-gap emitter transistors fabricated by the thin-film deposition of CdS on to Si are described. It is practically demonstrated that the resulting non-epitaxial junction between the CdS and Si does not inhibit the successful working of the transistors. Common emitter current gains of up to 80 were obtained with some devices. The magnitude of the gain and the gain-current level behaviour of the devices is explained in terms of interface transmission and recombination currents. High-gain experimental devices display a constant current gain at relatively high emitter currents, which is shown to be consistent with the interface recombination current arising predominantly from surface recombination in the Si. Values of capture cross sections of surface state in the Si are obtained which are comparable with those obtained by other workers. The common emitter current gains of the devices are found to be influenced greatly by the resistivity of the CdS emitter thin film.