chapter  14
18 Pages

Compound Semiconductor Devices for Digital Circuits

Consider a generic electron device as represented in Fig. 14.1. It consists of three electrodes encompassing a charge

transport region

. The transport region is capable of supporting charge flow (electrons as shown in the figure) between an

emitting electrode

and a

collecting electrode

. A third electrode, called the

control electrode

, is used to establish the electron concentration within the transport region. Placing a

control charge

, Q

, on the control electrode establishes a

controlled charge

, denoted as –Q, in the transport region. The operation of active devices depends on the

charge control principle:

Each charge placed upon the control electrode can at most introduce an equal and opposite charge in the transport region between the emitting and collecting electrode.