POINT-CONTACT TRANSISTOR SURFACE EFFECTS 



791 



The measured resistivity of the germanium used in this experiment 

 was 3.3 to 3.6 fl-cm. It can be seen from Curves I and II that increase 

 in the magnitude of the floating potential near the unformed point on 

 the etched surface after the HF treatment is, to a rough extent, propor- 

 tional to the increase in /c(0, — 10) produced by the treatment. Values 

 of 2irVpr/I taken from lines of slope ( — 1) drawn for best fit through 

 points on the individual curves give reasonable agreement with the 

 measured resistivity. For curve I, 27r F^r// = 3.3 ohm-cm, and for 

 Curve II, 2TrVpr/I = 3.5 ohm-cm. 



By comparing Curves I and II of Fig. 2 with Curves I and II of Fig. 

 12, it can be seen that the effect of treating the surface under the un- 

 formed point with HF is analogous to adding donor to the formed point 



-10 



CURRENT, Ic.lN MILLIAMPERES 

 -7 -6 -5 -4 -3 -2 



Fig. 11 ■ — Type (1) collector anomaly observed in unformed unit (n-t,\])e 

 germanium) . 



