Fig. 1 — Equivalent circuit for contact rectifier. The parallel components k and C repre- 

 sent the barrier layer itself and R,, represents the resistance of the hody of the semicon- 

 ductor. 



io 



EXHAUSTION 

 REGION 



^y "-TOTAL 



DISTANCE INTO SEMICONDUCTOR, X *■ 



Fig. 2 — Schematic eneig\' le\el diagram of p-lype semiconductor in conlaci wilii a 

 metal. The diagram is plotted ujjside down from the usual way in onler to show the energ\- 

 of holes increasing upward. The energ_\' of electrons increases tlownward. The lower diagram 

 gives the density of charge in the harrier la\cr. In the body of the semiconductor the s])ace 

 charge of the holes is compensated b)- the space charge of the negati\el\ iharged acce])tor 

 ions. Holes are drained out of the barrier la_\er bv the electric tield, leaving the negative 

 space charge of the acceptors. The rise in electrostatic potential in the barrier region re- 

 sults from this negative sjiace charge together with the comjiensating jjositive charge 

 on the metal. The capacitance of the barrier layer is api)roximalel\' that of a parallel 

 l)latc condenser with plate sejjaration (. 



429 



