Verfahren zum Herstellen eines p-n-UEbergangs in einer einkristallinen Halbleiteranordnung

966,257. Semi-conductor devices. SIEMENS-HALSKE A.G. May 10, 1962 [May 10, 1961], No. 17968/62. Heading H1K. An element suitable for use in a transistor is made by epitaxially growing on a donor and acceptor doped monocrystalline semi-conductor body in which the impurity in excess has the lower diffusion coefficient a layer of the same semi-conductor by thermal decomposition of a gaseous compound thereof. The impurities are caused to diffuse into the layer in the deposition process or in a subsequent heating so that only the impurity with the higher diffusion coefficient reaches its surface. In a typical case in which a P+ germanium crystal containing boron, indium or gallium as acceptor and phosphorus, arsenic or antimony as donor has had pure germanium deposited on it the diffusion produces the impurity distribution shown in Fig. 1. Beyond the PN junction (collector) formed at 21 the net impurity concentration No - N A rises to a maximum before falling again. Acceptor material may be alloyed into the high resistivity surface thus produced to form a low capacity junction (emitter), the internal higher conductivity region giving the N-type (base) zone a low overall resistance. The impurity distribution may be modified by incorporating donor material in the deposited material or by varying the rate of deposition. For instance by gradually increasing the deposition rate the distribution of Fig. 5 is obtained, while a sudden increase in deposition rate of 2111 gives the distribution shown in Fig. 3. Recombination centre impurities such as gold and nickel, may be incorporated in the base crystal or deposited material if desired. If an N-type silicon base crystal is used suitable acceptor impurities are aluminium, gallium, indium and boron and antimony and arsenic are suitable donors. Phosphorus is also suitable if aluminium is used as acceptor.