ELECTROLYTIC SHAPING OF GERMANIUM AND SILICON 



335 



[in 10 per cent KOH are shown in Fig. 1. Tlie concentration of KOH 



[is not critical and other electrolytes give similar results. The voltage 



'drop for the p-type specimen is small. For anodic n-type germanium, 



! however, the barrier is in the reverse or blocking direction as evidenced 



by a large voltage drop. The fact that n-type germanium differs from 



p-type germanium only by very small amounts of impurities suggests 



that the barrier is a semiconductor phenomenon and not an electro- 



i chemical one. This is confirmed by the light sensitivity of the n-type 



1 voltage-current characteristic. Fig. 2 is a schematic diagram of the 



! arrangement for obtaining voltage-current curves. A mercury-mercuric 



loxide-10 per cent KOH reference electrode was used at first, but a gold 



(wire was found equally satisfactory. At zero current, a voltage Vo exists 



j between the germanium and the reference electrode ; this voltage is not 



[included in Fig. 1. 



I The saturation current Is , measured for the n-type barrier at a 

 \moderate reverse voltage (see Fig. 1), is plotted as a function of tempera- 

 Iture in Fig. 3. The saturation current increases about 9 per cent per 

 [degree, just as for a germanium p-n junction, which indicates that the 



I 



40 



35 



30 



^25 



Lil 



O 20 



15 



10 



10 20 30 40 50 60 



CURRENT FLOW IN MILLIAMPERES PER CM^ 



Fig. 1 — Anodic voltage-current characteristics of germanium. 



