Power semiconductor components: distinctive features

In terms of their physical operating principles, power semiconductor components do not differ fundamentally from their analog or digital signal processing counterparts. What distinguishes them is their function in power electronics, which is that of switches, even more so than the orders of magnitude of switchable voltage and current, which are sometimes emphasized for their spectacular nature (8kV/3kA, for example, for such a Gate-Turn-Off thyristor). Whatever the power level, in fact, the emphasis is on characteristics such as blocked voltage, on-state current, turn-on and turn-off times, static and switching power losses... with specifications that require a completely different organization of semiconductor structures than that of microelectronic components.

For too long, the world of semiconductors - physicists, technologists, component designers and manufacturers - and the world of electrical engineering, to which the power electronics community belongs, have communicated little about power components other than through market studies and catalog data. Paradoxically too, electrical engineering, a generalist discipline if ever there was one, has always been interested in magnetic and dielectric materials, right down to the fundamental level, but has neglected semiconductors until recently.

Today, the sophistication of power electronics applications means that component designers can no longer ignore the specifics and constraints of their implementation, just as power electronics engineers cannot fully exploit the potential of modern power components without understanding their inner workings.

This booklet is therefore the general introduction to a series of articles dealing successively with the electronic properties of silicon, the main semiconductor material used, elementary semiconductor structures and the fundamental effects they give rise to, and the voltage withstand capability of power components, a generic subject, before dealing more specifically with the operating principles and the study of the static and dynamic characteristics of the main power components currently in use. A complementary article provides an overview of recent developments in the field of power integration.

This very introductory chapter, the design of which owes much to exchanges of views between the author and Professor Henri Foch, presents power semiconductors in terms of their function, their specific features compared with other semiconductor components, and their current performance.