Hole Injection in Germanium — Quantitative Studies 

 and Filamentary Transistors- 



By 



W. SHOCKLEY, G. L. PEARSON and J. R. HAYNES 



Holes injected by an emitter i^oint into lliin single-crystal filaments of german- 

 ium can he detected by collector jioints. From studies of transient phenomena the 

 drift velocity and lifetimes (as long as 140 microseconds) can be directly observed 

 and the mobility measured. Hole concentrations and hole currents are measured 

 in terms of the modulation of the conductivity ])roduced by their presence. 

 Filamentarv transistors utilizing this modulation of conductivity are described. 



1. Introduction 



THE iiwention of the transistor by J. Bardeen andW. H. Brattain'' -■ =' 

 has given great stimulus to research on the interaction of holes and elec- 

 trons in semiconductors. The techniques discussed in this paper for investi- 

 gating the behavior of holes in w-type germanium were devised in part to aid 

 in analyzing the emitter current in transistors. The early experiments sug- 

 gested that the hole flow from the emitter to the collector took place in a 

 surface layer.^' - The possibility that transistors could also be produced by 

 hole flow directly through w-type material was proposed in connection with 

 the p-n-p transistor.^ Quite independently, J. N. Shive^ obtained evidence 

 for hole flow through the body of »-type germanium by making a transistor 

 with points on opposite sides of a thin germanium specimen. Such hole flow 

 is also involved in the coa.xial transistor of W. E. Kock and R. L. Wallace." 

 Further evidence for hole injection into the body of »-type germanium under 

 conditions of high fields was obtained by E. J. Ryder.' 



In keeping with these facts it is concluded^ that with two points close 

 together on a plane surface, as in the type-A transistor , holes may flow 

 either in a surface layer or through the body of the germanium. For surface 

 flow to be large, special surface treatments appear to be necessary; such 

 treatments were not employed in the experiments described in this paper 

 and the results are consistent with the interpretation that the hole current 

 from the emitter point flows in the interior. 



The experiments described in this paper, in addition to any practical 

 implications, serve to put the action of emitter points on a quantitative basis 

 and to open up a new area of research on conduction processes in semicon- 



* It is planned to incorporate this material in a book entitled "Holes and Electrons, 

 an Introduction to the Physics of Transistors" currently being written by VV. Shockley. 

 This book is to cover much of the material planned for the "Quantum Physics of Solids" 

 series which was discontinued because of the war. 



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