Simple Classical Theory of Conduction
John P. Xanthakis · 2020
This chapter explains an account of the elementary or standard theory of classical conduction, i.e. the theory which is based on the continuity and the drift–diffusion equations. It deals with the relation between applied voltages and observed currents in both semiconductor materials and devices. When the two neutral semiconducting pieces make contact with each other, electrons from the N-type semiconductor will diffuse to the P-type and likewise holes from the P-type semiconductor will diffuse towards the N-type. The positively charged donors in the N-type semiconductor and the negatively charged acceptors in the P-type semiconductor near the surface create an electric field E whose direction opposes the further diffusion of electrons and holes. Once the barrier to jumping across to the other side has been reduced, the diffusion currents Jndiff and Jpdiff have increased exponentially with the applied voltage because of an exponentially increased injection of the two types of majority carriers to their opposite side.