GB1015985A - Semiconductor materials and applications thereof - Google Patents

Abstract

The Specification relates to the use in semiconductor devices of various boron-carbon and boron-carbon-based compositions. It describes their use in thermo-electric elements, thermistors, point-contact rectifiers, and frequency sensitive capacitors. These compositions contain 6.5 - 17 weight per cent carbon and may contain one or more additional elements selected from all parts of the Periodic Table with the exception of the halogens and the rare gases. Table I in the Specification sets out many additives and the proportions in which they may be used. The lower limit for the additives is 10-13 weight per cent; the upper limit, which varies slightly with the nature of the additive, is never more than 25 weight per cent for a single additive or more than 48 weight per cent for combinations of additives. The compositions may be formed by hot-pressing mixtures of the powdered elements. Decomposition of a mixture of an alkyl boron compound with or without diborane or a boron trihalide will also yield carbon boron mixtures of the required proportions, additional elements such as aluminium, titanium, iron, germanium, and silicon being incorporated by co-deposition of their hydrides or halides. Specific compositions disclosed are: (1) 93.49% B, 6.5% C, 0.01% Ge; (2) 89.9% B, 10% C, 0.1% Si; (3) 88.75% B, 11% C, 0.2% Si, 0.05% Ti; (4) 88% B, 10% C, 2% Ce; (5) 86% B, 7% C, 7% Be; (6) 85.6% B, 12% C, 1.5% Ti, 0.9% Si; (7) 85% B, 15% C; and (8) 83% B, 12% C, 5% Ge. Three compositions are disclosed in which the value of the carbon content within the range 6.5 - 17% is not specified but which contain respectively 0.0001 atom per cent Be, 0.00001 atom per cent Si, and 0.001 weight per cent Mn.ALSO:Air or another oxygen source and a stream of liquid white phosphorus are fed into a furnace for the production of phosphoric anhydride. The hot exit gas stream containing the phosphoric anhydride is cooled by passing it over a surface containing thermoelectric elements consisting of carbon-boron or carbon-boron-base compositions containing 6.5-17 wt. per cent carbon. The furnace described has four thermoelectric units connected in series so that the heat absorbed gives a useful electrical output such as that required for a motor or a resistive load. Alternatively power may be fed into the thermoelectric elements of the phosphorus burner or similar furnace so that with one direction of current flow the units act as a Peltier cooler and with the opposite direction of current flow the junctions in contact with the gas-stream provide heat to initiate a reaction.