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BELL SYSTEM TECHNICAL JOURNAL 



from Eq. (38). Taking a = 1, /i = 0.5, a,, = 0.14,6 = 1.5, A = 10-« and 

 rft = 5 X 10"\ we get 



G{ih)/ pa) '^' 100 micromhos. 



(50) 



This value is of the same order as the values obtained from Suhl's data 

 listed in Table III. There is a large scatter in the latter and the values are 



Table II 

 Calculation of hole concentrations from probe potential measurements. A V measures 

 potential difference resulting from hole injection of 1 ma when total current is kept at 4 

 ma; data from H. Suhl. 



Table III 

 Changes in conductance resulting from application of magnetic field and from hole 

 injection. Units are micromhos. Data from H. Suhl. 



not consistent. It has been suggested that the abnormal values may result 

 from local sources of holes. 



IV. Hole Flow for a Collector with Large Reverse Voltage 



Haynes has shown that there is a linear relation between the current 

 to a collector point operated in the reverse direction and the concentra- 

 tion of holes in the interior of a germanium filament. Under the conditions 

 of his experiment, the current flowing to the collector point is small com- 

 pared with the total current flowing down the tllament, so that the col- 

 lector current does not alter the concentrations very much. Moles are 

 injected into the filament by an emitter point placed near one end, and 

 the concentration is determined from the change in resistance of the 

 filament in the neighborhood of the collector point. 



