Hole Injection in Germanium - Quantitative Studies and Filamentary Transistors

HE invention of the transistor by J. Bardeen and W. H. B r a t t a i n 1 , has given great stimulus to research on the interaction of holes and electrons in semiconductors. T h e techniques discussed in this paper for investigating the behavior of holes in w-type germanium were devised in part to aid in analyzing the emitter current in transistors. T h e early experiments suggested t h a t the hole flow from the emitter to the collector took place in a surface layer. 1 ' 2 T h e possibility t h a t transistors could also be produced by hole flow directly through w-type material was proposed in connection with the p-n-p transistor. 4 Quite independently, J. N. Shive 5 obtained evidence for hole flow through the body of w-type germanium by making a transistor with points on opposite sides of a thin germanium specimen. Such hole flow is also involved in the coaxial transistor of W. E. Kock and R. L. Wallace. 6 F u r t h e r evidence for hole injection into the body of w-type germanium under conditions of high fields was obtained by E. J. Ryder.' In keeping with these facts it is concluded 3 that with two points close together on a plane surface, as in the type-A transistor 8 , holes m a y flow either in a surface layer or through the body of the germanium. For surface flow to be large, special surface t r e a t m e n t s appear to be necessary; such t r e a t m e n t s were not employed in the experiments described in this paper and the results are consistent with the interpretation t h a t the hole current from the emitter point flows in the interior.