Verfahren zum Herstellen eines Halbleiterbauelements

928,562. Semi-conductor devices. WESTERN ELECTRIC CO. Ltd. July 12, 1961 [July 18, 1960], No. 25221/61. Class 37. In making a semi-conductive device containing at least one PN junction a directional elastic strain is produced and maintained in the semiconductive material and if of a magnitude such that the carrier mobilities in the material are altered by at least 15%, the strain direction being aligned with respect to a crystallographic direction of the material. A theoretical discussion of the effect is given and includes data relating to the choice of the strain direction. In the mesa-type transistor shown in Figs. 2 and 3 the stressing of the P-type germanium wafer 5 serving as the collector communicates a compressive strain to the N-type base region 11 bearing a heavily doped P-type base contact 12 and an N-type emitter region 13 and simultaneously increases the mobilities of electrons in the direction across the base zone and of holes in the plane of the zone. The three other embodiments described, Figs. 4, 5, 6 (not shown) are a NPN transistor, a PNP mesa-type transistor, and a P+NN+ varactor diode, and these are stressed in differing ways: the plane germanium wafer of the NPN transistor is hard soldered at its ends to the surface of a block which is bent about a fulcrum to apply tensile strain to the wafer; the P-type collector wafer of the PNP mean-type transistor is hard soldered to the end face of a metal pin held under biaxial radial compression and the force on the pin them removed thus applying biaxial tension to the wafer and the N-type mesa on its other surface; the base region of the varactor diode is hard soldered or otherwise attached to a heated bar which is then allowed to cool, thus setting up a compressive strain in the diode. Semiconductive materials suitable for using the effect are:- Si, Ge, InSb, PbTe, GaSb, AgSbTe 2 , AgSbTe, Cu 3 AsS 4 , Cu 3 AsS 3 , Cu 3 SbS 3 , Bi 2 Te 3 , Bi 2 Se 3 , Sb 2 Te 3 , PbSe, CdS, ZnO, AgSbSe 2 .