An N-P-N high power fast germanium core driver transistor

An n-p-n alloyed germanium core driver transistor has been designed and developed which has been typical turn-on, turn-off, and storage times of 0.2-0.4 µsec at an output current of 0.5 a, and dissipates 3 watts with the heat sink kept at room temperature. Conflicting electrical and thermal requirements were simultaneously achieved by soldering the germanium wafer on a thick copper tab which was in turn mounted on the metal base. Switching times were improved by reducing the volume available for minority carrier storage. Current gain, which for most units is over 100 at 0.5 a, was increased by optimizing the transistor geometry. The design considerations and transistor performance as well as data of 100°C storage life test are presented.