Chapter 1 showed that a junction between n-type and p-type materials has asymmetrical conducting properties enabling it to be used for rectification. A bipolar transistor includes two such junctions arranged as shown in Fig. 2.1. Fig. 2.1(a) illustrates one basic type consisting of a layer of n-type material sandwiched between two layers of p-type material: such a transistor is referred to as a pnp-type.
A second type, illustrated in Fig. 2.1(b), has a layer of p-type material sandwiched ...