Characteristics of Compound Barrier Layer Rectifiers

The assumptions involved in Mott's and Schottky's theories of rectification are analysed and a potential barrier at the metal-semiconductor interface is proposed which enables one to pass continuously from one theory to the other. The model is directly applicable to the practically important case of rectifiers possessing an additional insulating layer between semiconductor and counter-electrode. The current-voltage characteristic of such a compound barrier is obtained and contains Mott's and Schottky's results as special cases. In this connection, an expression for the volume distribution of current carriers is obtained and plotted for the case of a linear potential distribution in the barrier. A discussion of the distribution of charges throughout the rectifier leads naturally to the concept of a capacitance of the barrier, and to the derivation of the capacitance-voltage characteristic. In this connection, a definite experimental problem is suggested by the analysis.