A High-Frequency Diffused Base Germanium Transistor

Abstract

Techniques of impurity diffusion and alloying have been developed which make possible the construction of p-n-p junction transistors utilizing a diffused surface layer as a base region. An important feature is the high degree of dimensional control obtainable. Diffusion has the advantages of being able to produce uniform large area junctions which may be utilized in high power devices, and very thin surface layers which may be utilized in high-frequency devices. Transistors have been made in germanium which typically have alphas of 0.98 and alpha-cutoff frequencies of 500 mc/s. The fabrication, electrical characterization, and design considerations of these transistors are discussed.