Medium-power high-speed PNP and NPN germanium alloy transistors

A Bell System application requires a complementary pair of medium power, high speed switching transistors which, among other requirements, must show an alpha cut-off frequency of greater than four megacycles/second and electrical punch-through voltage of twenty-five volts minimum. Units have been designed and produced which exhibit median values of these parameters of seven megacycles/second and seventy volts, respectively. High yields have been achieved on established production lines by very close manufacturing controls of the critical alloying variables, namely: germanium wafer thickness, alloyed junction area, concentricity, mass of alloying material, alloying temperature, and special material properties such as orientation and etch-pit density. The precision gauging and jigging methods which were developed in conjunction with the Western Electric Company and results obtained will be presented.