Schrittschalteinrichtung mit einem Halbleiterkoerper und mit einer Reihe von abwechselnd leitenden Wegen

845,120. Semi-conductor switching and multistable state circuits. WESTERN ELECTRIC CO. Inc. March 29, 1957 [April-18, 1956], No. 10359/57. Class 40(6). [Also in Groups XIX, XXXVI and XXXVIII] In a device comprising a semi-conductor body including a plurality of separate conducting paths each having a high impedance state and a low impedance state the paths are so arranged relative to one another that operation of one path in its low impedance state primes an adjacent path for transfer to its low impedance state. In the device shown in Fig. 1 each path comprises separate P and N portions 11 A-D and 27A-D, and common P and N zones 13, 14. The separate N type zones are asymmetrically arranged with respect to the separate P type zones so that when path B for instance, is operating in its low impedance state carriers are traversing the part of the common P type zone beneath the extension 27C of the N type zone associated with the adjacent conduction path C. Consequently when a potential greater than the minimum sustaining potential for low impedance operation of path C is applied to that path by throwing switch 21 to its lower position current is diverted from N type zone 27B to the extremity or starter portion of N type zone 27C. Current flow then advances along the junction 17 to the preferred path of conduction immediately beneath the junction 15C. This effect occurs only if the switching action takes less time than the lifetime of an electron in zone 13 and the transit time of electrons across the zone. Current path A remains in its high impedance state since the starter portion of its N type zone 27A is too remote from current path B to be primed. The lateral extent of the region of the junction 17 through which minority carriers are emitted when the current path B is in its low impedance state, as shown in Fig. 2 depends on the lateral resistance of the zone 13 and determines the maximum spacing between the edge of junction 16B and the edge of starter portion 27C for which priming occurs. The Specification includes a mathematical treatment of the effects described above. It is stated that the existence of two stable conduction states in each path is due to change of the current multiplication α with current. Such changes of α may be enhanced by introduction of impurities, such as iron in silicon or nickel in germanium, or by bombarding with high or intermediate energy particles to produce crystal dislocations. In an alternative arrangement suitable for us