Abstract :
This paper will discuss experimental P-N-P and N-P-N power transistors having low collector leakage, high breakdown voltage and high current gain. P-N-P transistors have been made with d.c. current amplification factors as high as 140 at 1 ampere, collector leakage current on the order of 20 microamperes and collector breakdown as high as 200 volts. These characteristics are attributed in part to the use of special junction alloys consisting of indium and gallium or aluminum. N-P-N transistors having leakage and voltage breakdown characteristics similar to the P-N-P transistors have been made with d.c. current amplification factors as high as 200 at 1 ampere. An alloy of arsenic in lead is used for both the emitter and collector junctions. Other considerations in the design of power transistors such as base lead resistance, emitter to collector punch through, and thermal drop will be discussed. Typical characteristics of transistors designed for Class B amplifier use as well as high voltage switching applications will be presented.
