Quantum Processes in Semiconductors 5th Edition

Book Preface

Semiconductor physics is of fundamental importance in understanding the behaviour of semiconductor devices and for improving their performance. Among the more recent devices are those exploiting the properties of III–V nitrides, and others that explore the technical possibilities of manipulating the spin of the electron. The III–V nitrides, which have the hexagonal structure of wurtzite (ZnO), have properties that are distinct from those like GaAs and InP, which have the cubic structure of zinc blende (ZnS). Moreover, AlN and GaN have large band gaps, which make it possible to study electron transport at very high electric fields without producing breakdown. This property, combined with an engineered large electron population, makes GaN an excellent candidate for high-power applications. In such situations the role of hot phonons and their coupling with plasmon modes cannot be ignored. This has triggered a number of recent studies concerning the lifetime of hot phonons, leading to the discovery of new physics. An account of hot-phonon effects, the topic of the first of the new chapters, seemed to be timely.

In the new study of spintronics, a vital factor is the rate at which an out-of-equilibrium spin population relaxes. The spin of the electron scarcely enters the subject matter of previous editions of this book other than in relation to the density of states, so an account of spin processes has been overdue, hence the second of the new chapters in this edition. The rate of spin relaxation is intimately linked to details of the band structure, and in describing this relationship I have taken the opportunity to describe the band structure of wurtzite and the corresponding eigenfunctions of the bands, from which the cubic results are deduced. There are several processes that relax spin in bulk material, and these are described.

The properties of semiconductors extend beyond the bulk. All semiconductors have surfaces and, when incorporated into devices, they have interfaces with other materials. The physics of metal– semiconductor interfaces has been studied ever since the discovery of rectifying properties in the early part of the 20th century. More recently, the advent of so-called low-dimensional devices has highlighted problems connected with the physics of interfaces between different semiconductors, so an account of the properties of surfaces and interfaces was, it seemed to me, no longer timely, but long overdue. Hence, the third new chapter.

This new edition is therefore designed to expand (rather than replace) the physics of bulk semiconductors found in the previous edition.  Theexpansion has been motivated by the subject matter of my own research and that of colleagues at the Universities of Essex and Cornell.
I am particularly indebted to Dr Angela Dyson for her insightful collaboration in these studies.

Thorpe-le-Soken, 2013 B.K.R