Summary of semiconductor theory.

In this section we have described how the natural conduction properties of semiconductors like silicon, can be modified by doping pure semiconductor, with a specific amount and type of impurity. This creates two types of artificial or extrinsic semiconductor material, called N and P type semiconductor.

When these materials are used to construct basic components, we have seen that applied voltages can control the number of mobile charge carriers present, in particular regions within the device, (e.g. the control of depletion regions etc.). This enables diodes to block current flow in one direction, and also enables the current flowing between two terminals of a transistor, to be controlled by the voltage applied to the third terminal.

The transistor is a very important electronic component and forms the basis of many important electronic circuits. We have considered the two "families" of transistors (BJTs and FETs) and discussed some of their comparative benefits and disadvantages.

Finally we considered a basic overview of the stages of semiconductor manufacture.

There are other semiconductor devices that haven't been covered in this section, such as triacs and thyristors. However many of the circuits you will initially encounter in analogue and digital electronics, contain the components introduced in this section. As you encounter new components you should find that the same principles covered in this section, can be applied to understand how they function.