Abstract:
A semiconductor device comprising contiguous layers of crystalline selenium and cadmium selenide with a P-N heterojunction therebetween disposed on a high work function electrode. A thin tellurium film is disposed between the electrode and the selenium layer, and acts as a buffer to provide compatibility between the selenium crystalline structure and the structure of the underlaying electrode. When employed as a stress-sensitive transducer, the device is disposed on a flexible substrate. The device may also be employed as a thin-film diode.
Abstract:
A low dark current photoconductive body includes an aluminum oxide overlayer on a cadmium selenide base layer. A transition region is provided at the interface region between the base layer and the overlayer and consists of a graded transition of cadmium and selenium with increasing amounts of aluminum and oxygen. An alternative body is disclosed omitting the overlayer. A blocking contact is provided within a portion of the body including the overlayer and/or the transition region.
Abstract:
A photo-conductive material for use in photoelectric cells (see Group XXXVI) is made by mixing cadmium sulphide, selenide or sulphoselenide with a flux, firing above the melting point of the flux and washing out the crystals from the resulting product, firing the washed crystals to sinter them into a mass, breaking up the mass into powder without grinding and finally firing the powder in a third firing below the sintering temperature at least part of which is carried out under atmospheric pressure in the presence of sulphur. In a specific example 100 grams of cadmium sulphide or selenide or a mixture of the two is mixed with 10 grams of cadmium chloride, 1 gram of ammonium chloride 0.7 ml. of 0.1 mol. copper chloride and 25 ml. water and the mixture dried at 150 DEG C. for 15 hours, broken up and fired at 600 DEG C. for 20 minutes. The fired mass, consisting of CdS crystals impregnated with Cu and Cl is soaked and washed in water to remove most of the CdCl2, then moistened with a solution containing equal parts of 0.1 mol. CdCl2 and 1 mol. NH4Cl and passed through a 325-mesh sieve. It is then fired at 600 DEG C. for 20 minutes and the sintered mass resulting is grated through a 50-mesh sieve, and is fired in the presence of sulphur vapour for 10 minutes at 500 DEG C. and for a further 10 minutes in vacuo. After cooling it is passed through a 325-mesh sieve. Ag or another monovalent iron may replace Cu. In a further embodiment cadmium sulphide is crystallized from a mass comprising 10 per cent by weight of a molten flux containing a halide and the flux leached out. Cu is added and diffused into the CdS in a second firing.
Abstract:
A rectifying junction suitable for use in photosensitive devices is fabricated between a polycrystalline selenium layer and an electrode of n-type or low work function metal material.