Fused Impurity P-N-P Junction Transistors

Fused impurity p-n-p junction transistors have been made which exhibit the useful circuit characteristics of high-gain, low-noise figure and alpha slightly less than unity. Such transistors are well adapted for application involving high ambient temperatures or high dissipation levels since alpha remains very nearly constant up to 120 degrees C and decreases somewhat above this temperature, permitting their stable use in emitter-grounded circuits at high temperatures. This is in contrast to junction transistors having high-resistivity collector regions, for which alpha often rises above unity at high temperatures leading to circuit instability. Satisfactory operation at several watts collector dissipation has been achieved.