POINT-CONTACT TRANSISTOR SURFACE EFFECTS 



779 



Vr = -20 VOLTS 



Vp = -20 VOLTS 



0.25% CUSO4 (PULSE TIME =: 10//S) 025"y<, CUSO4 (PULSE TIME = lO/ZS) 



Mi LS 



Vq = -20 VOLTS 



(PULSE TIME = 10/uS 1 



Vg = -20 VOLTS 

 [PULSE TIME = 10/US) 



Fig. 6 — CopiJer plated formed layers in point-contact transistors. 



collector, the pattern obtained is more difficult to interpret, Fig. 6(a) 

 and (c). However, in both cases the disturbed areas are roughlj^ compa- 

 rable in shape and size. 



Differences in the forward characteristics of the collector and emitter 

 points may also be graphically observed by means of the plating tech- 

 nique. In Figs. 7(a) and 7(b) are sketches of patterns obtained by applj'- 

 ing forward bias to contacts for plating. In this case a more concentrated 

 solution is used, and the plating time is longer. In Fig. 7(a) is shown 

 the pattern obtained when an unformed collector point is biased for- 



