| 摘要 |
<p>1,157,719. Semi-conductor devices. WESTINGHOUSE ELECTRIC CORP. 12 Jan., 1968 [27 Jan., 1967], No. 1880/68. Heading H1K. [Also in Division H3] An SCR assembly comprises two complementary transistors, the base and collector of one being connected to the collector and base respectively of the other, one of the transistors having an equivalent rectifier connected directly between its emitter and base regions so that the apparent common-emitter current gain of the combination of the transistor and the rectifier is less than unity. The arrangement provides a device with appreciable turn-off gain. As shown, Fig. 1, the PNP transistor is constructed so that over the major portion of the base region 16 no transistor action occurs, this portion constituting the equivalent rectifier. This results in the transistor having a common-emitter current gain of less than unity. The NPN transistor is connected to the PNP transistor by means of ohmic contacts 30, 32. The product of the current gains of the transistors is greater than unity. When the device is switched on by a voltage applied to the gate terminal the bulk of the load current flows through the base circuit of the PNP transistor rather than through the collector circuit due to its low current gain. The device can be switched off by withdrawing current from the gate terminal to prevent the collector current of the PNP transistor from flowing into the base of the NPN transistor. The PNP transistor 10 may be produced by diffusing an N-type impurity into the lower face of a P-type silicon wafer to form the base region and then masking and diffusing-in a P-type impurity to form a small-area collector region. The NPN transistor 12 may be produced by diffusing a P-type impurity into the upper face of an N-type silicon wafer to form the base region and then masking and diffusing-in an N-type impurity to form a large-area collector region. The ohmic contacts 30, 32 may be of silver.</p> |
