Electronic Devices

About this unit

This unit introduces the physics behind modern electronics. It starts with energy bands in solids, which explain why some materials are conductors, some insulators and some semiconductors. It then examines semiconductors in detail: intrinsic semiconductors, and how adding tiny amounts of impurity (doping) produces n-type and p-type materials with electrons or holes as majority carriers. Joining p-type and n-type material makes a p-n junction, the basis of the diode. You will study how a depletion region and barrier potential form, the diode's behaviour in forward and reverse bias, and its use as a rectifier to convert alternating current into direct current.

How to prepare

Learn the band-gap ranges for conductors, semiconductors and insulators and how conductivity of a semiconductor changes with temperature. Memorise which dopants give n-type and p-type material and the relation nₑnₕ = nᵢ². Understand depletion layer formation, the I-V graph in both biases and the working of half-wave and full-wave rectifiers. Practise simple numericals on band gap wavelength, carrier concentration and diode circuits.