476 



BELL SYSTEM TECHNICAL JOURNAL 



mental arrangement is illustrated in Fig. 2. Holes are injected into a 

 germanium filament by an emitter point and the circuit is closed by 

 allowing the current to flow to the large electrode at the left end. The 

 right end of the filament is left floating. Some of the injected holes diffuse 



HOLES INJECTED 



FLOATING POTENTIAL, Vnr, 



AND CONDUCTANCE, Y, 



MEASURED 



Fig. 2. — Schematic diagram of experiment of G. L. Pearson to investigate relation be- 

 tween floating potential and impedance of point contact. 



>"6 



Z 3 



o 



< 2 



_j 



UJ 



a. 

 (.5 



0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 



FLOATING POTENTIAL, Vf , IN TERMS OF KT/e 



Fig. 3. — The relationship of admittance ratio to potential, measured at a point on a 

 germanium filament into which holes are emitted, with no current flow, from G. L. Pear- 

 son's data of September 21, 1948. 



down the filament and increase the local concentration in the neighbor- 

 hood of the probe point. This concentration can be varied by changing 

 the emitter current and also by changing the distance between emitter 

 and ])robe. Hoth the floating potential and the conductance between the 

 prol)c point and the large electrode on the right end were measured. 

 L'nder the conditions of this experiment, the potential drop in the in- 



