Research On the semiconductor materials started in the early nineteenth century. Since then, many semiconductors have been investigated. Certainly the most well known material are Silicon Si and germanium Ge, which both belong to column IV of the periodic table of elements. While a bulk crystal of Si or Ge consist of periodic arrangement of a single atom, other semiconductors like gallium arsenide GaAs (III-V) are built with different elements: Ga (III) & As (V).Such composite semiconductors have electrical or optical properties that are not achievable with pure semiconductor made of only one type of atom.
Just as the late eighteenth through nineteenth centuries are known as the industrial age due to the rise of mechanization, the twentieth century can be referred to as the beginning of the electronic age. The first half of the century was dominated by electronic vacuum tubes that made possible devices such as radio, television, radar and long distance telephone. The technology of the vacuum tube was displaced mid-century by the introduction of solid-state semiconductors. The first working prototype transistor was invented at Bell Labs in 1947 by John Bardeen, Walter Brattain and William Shockley. This device, properly referred to as a point contact transistor, was quickly superseded by the bipolar junction transistor, a major topic of this text. Commercial production of the transistor and related devices improved the performance of existing applications and made possible a range of new ones. Semiconductors proved to be smaller, lighter, more reliable and less expensive to build than their vacuum tube counterparts. The last 30 or so years of the century saw the rapid expansion of the integrated circuit where numerous transistors are combined in a single device. Initially such a device may have contained the equivalent of a dozen or so individual semiconductor devices, but today that number has grown to the billions 1 . This extreme density has given rise to now common-place applications such as cell phones, GPS devices, laptop computers, tablets and our global communications infrastructure.
The science writer, Arthur C. Clarke, once observed that “Any sufficiently advanced technology is indistinguishable from magic”. Indeed, although today the typical citizen living in an industrialized country makes use of numerous electronic devices each day (sometimes without even being aware of it); they typically have scant knowledge of how these devices “work their magic”. Obviously there is no magic, only the application of scientific principles mixed with human ingenuity. Further, just as it is true that many more people can use a cell phone than design one, it is also true that there is a greater need for people who can design, manufacture and maintain devices based on semiconductors than for people who design the semiconductors themselves. The scope of this text, then, focuses on the operation and application of semiconductor devices rather than the design of the semiconductor themselves.