252 



BELL SYSTEM TECHNICAL JOURNAL 



wise treated to give a surface suitable for transistor action. The collector 

 point was usually kept foed, since it is more critical, and the emitter point 

 moved. Measurements were made with formed collector points. Most of 

 the data have been obtained on surfaces oxidized as described below. 



As expected, the emitter current has less and less influence on the collec- 

 tor as the separation-^, s, is increased. This is shown by a decrease in i?2i, 

 or a, with s. The effect of the collector current on the emitter, represented 

 by the feedback resistance R12, also decreases with increase in 5. The 

 other coefficients, Ru and R^i, are but little influenced by spacing. Figures 



100 



^ 80 



O 



-. 60 



0.010 0.015 0.020 



SEPARATION IN CENTIMETERS 



Fig. 4 — Dependence of feedback resistance Rvi on electrode separation for two differ- 

 ent parts A and B, of the same germanium surface. The surface had been oxidized by 

 heating in air. 



4, 5 and 6 illustrate the variation of Rn and a with the separation. Shown 

 are results for two different collector points A and B on different parts of 

 the same germanium surface-^. In making the measurements, the bias 

 currents were kept fixed as the spacing was varied. For collector A, le = 

 1.0 ma and Ic = 3.8 ma; for collector B, /<, = l.U ma and /c = 4.0 ma. 

 The values of Rn and R22 were about 300 and 10,000, respectively, in both 

 cases. 



Figure 5 shows that a decreases approximately exponentiaUy with s 

 for separations from .005 cm to .030 cm, the rate of decrease being about 

 the same in all cases. Extrapolating down to 5 = mdicates that a further 



