Table Of ContentThe Story of Semiconductors
John Orton
OXFORD UNIVERSITY PRESS
The Story of Semiconductors
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The Story of Semiconductors
John Orton
Emeritus Professor, University of Nottingham, UK
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10 9 8 7 6 5 4 3 2
Al Cho ofBell Labs receiving the US National Medal ofScience
from President Clinton and Vice President Gore in 1993. Courtesy
ofAl Cho.
Enrico Capasso (left front) with the Bell Labs team which developed
the quantum cascade laser using energy states in conduction band
quantum wells in the AlInAs/GaInAs material system. Courtesy of
Lucent Technologies Inc.
Just to prove that even the most dedicated scientists do not spend all their time
in the laboratory – Hiroyuki Sakaki on the golfcourse at St Andrews in 1991.
Courtesy ofHiroyuki Sakaki.
Leo Esaki (left) and Hiroyuki Sakaki (right) deep in discussion ofthe properties of
advanced quantum well structures in 1976. Esaki won the Nobel Physics Prize in
1973. Courtesy ofHiroyuki Sakaki.
Preface
My wife and I bought our first television set in 1966, a major family
decision, which just happened to coincide with England’s soccer World
Cup success at Wembley Stadium. It cost us about £100 out of my then
salary of £2000 a year. Thirty years later, when I retired on a salary
some twenty times greater, the purchase of an infinitely superior
colour set priced at little more than £500 could be contemplated with
considerably less heart-searching. Indeed, the financial outlay involved
in watching England’s rugby World Cup success in 2003 gave us
scarcely a qualm, one measure, perhaps, of the quite remarkable trend
in consumer friendliness inherent in the modern electronics industry. In
this we see one of the great successes of capitalist philosophy—a highly
competitive business environment yielding previously unimaginable
value for the consumer, while providing relatively comfortable employ-
ment for a very large workforce and (in spite of recent setbacks, exem-
plified by the misfortunes of the Marconi company) a satisfactory
return on invested capital for its shareholders. But, more significantly
from the viewpoint of this book, we also see a business based fairly and
squarely on investment in scientific research. With the possible excep-
tion of the pharmaceutical industry, there has never been such a
commitment to organized R&D and never before has the marriage
between science and industry been so prolific in its progeny.
More specifically, this remarkable commercial success owes its exist-
ence largely to discoveries in semiconductor physics, which blossomed
during the first half of the twentieth century and to developments in
semiconductor technology and device concept, which followed the
exciting events of Christmas 1947 when Bell scientists realized the
World’s first successful solid-state amplifier. Here was vindication for
Bell’s commitment to basic solid-state research in an industriallaborat-
ory, which set the pattern for a rapidly expanding commercial activity,
an activity which has continued to grow at a remarkably consistent rate
into the present, truly worldwide industry we know today. It began
with germanium, which was immediately replaced by silicon, then
gradually drew in an amazing cohort of compound semiconductor
materials required to meet the rapidly diversifying range of device
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Preface
demands, based on an equally diverse range of applications. Today, we
take for granted the involvement of visible light and both infrared and
ultraviolet radiation as well as that of electrons. This expansive industry
is concerned with lighting, display, thermal imaging, solar electricity
generation, optical communications, compact disc audio systems, DVD
video systems, and a quite remarkable array of other uses for semi-
conductor lasers, as well as the more conventional electronic applications
typified by the personal computer. All in all, this omnipresent electronics
industry represents an annual turnover of about 5(cid:1)1011US$, a figure
that compares not unfavourably with the $2(cid:1)1012of the trend-setting
automobile industry.
It is little more than 50 years since the inception of transistor
electronics, a period which has seen quite dramatic developments in
semiconductor devices, an activity with which I was personally involved
for over 30 years. Having, during this time, written a number of books
and specialist review articles, I felt it worthwhile, on reaching retire-
ment, to attempt some kind of summary of the field in which I had
worked. It had seemed to me for some time that, in spite of the numer-
ous excellent texts which describe the physics and technology of semi-
conductor devices, there was a distinct lack of any coherent account of
just how these devices came into being. What were the driving forces,
what the difficulties to be overcome, what determined why a particular
development occurred when it did, where was the work undertaken
and by whom—in other words, how did the history of the subject
develop. As I became more and more interested in such questions, it
occurred to me that other workers in the field might appreciate a
reasonably concise account of its history, as background to their current
endeavours, also that there might be a wider audience of scientists who
would find a non-specialist account of this epoch-making activity of
general interest and, finally, that undergraduate students should be
encouraged to understand not only semiconductor physics and device
technology but also the background story of their advent. It is a human
story and, as such, may surely illuminate the technical aspects of the
subject to advantage. It is also a rapidly moving story and much of what
I have written will very soon be superseded, so I have made no attempt
to include the very latest developments. The account stops roughly
(and perhaps appropriately) at the millennium, my intention all along,
having been to write a history, not an up-to-date text book.
In most academic studies we expect to know something of the
people involved—who painted such and such a picture, who developed
such and such a philosophical idea, who was responsible for certain
political innovations—and it seems no less appropriate in science. The
difficulty here lies in the nature of modern scientific research, which
has become much more of a team activity, rather than that associated
with any one specific individual; so, in many cases, I have found it
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Preface
appropriate to refer to laboratories, rather than individuals. In attempting
a broad overview of the subject, it is scarcely possible to give an accurate
account of exactly how each individual scientist contributed to any
particular discovery and I have not even tried to do so. This must be the
task of the professional historian—and I make no pretence of being
one. Perhaps this can be taken as encouragement to serious historians
to become involved in the intricacies of scientific and technological
history. It is a vital part of modern culture and, as such, demands
considerably more attention than it currently receives. I only hope that
the present broad-brush account may serve as a stimulus to further,
more detailed studies.
Having said this, I should acknowledge that one or two detailed studies
do exist. I think, particularly, of the excellent ‘Crystal Fire’ by Michael
Riordan and Lillian Hoddeson, which describes the early work on tran-
sistors and integrated circuits, the ‘Electronic Genie’ by Frederick Seitz and
Norman Einspruch, covering somewhat similar ground and the admirable
survey of fibre optics provided by Jeff Hecht in his ‘City of Light’. Charles
Townes has also given us valuable insights into the origins of the laser in
‘How the Laser Happened’, though with rather little reference to semi-
conductor lasers. All these I have found helpful, as I have acknowledged in
the relevant parts of my own account. There is, though, considerable
scope for other studies, as anyone reading this book will appreciate. At
present, we are far better informed as to the details of Michael Faraday’s
researches in the early years of the nineteenth century than we are to the
development of group III-V semiconductors in the twentieth.
I have already outlined the audience to whom I have addressed this
book, and it covers, I accept, a rather broad spectrum. This has influ-
enced the format of the book in one important respect, the inclusion of
‘Boxes’ which contain the more specialized and mathematical detail
supporting the basic account given in the main text. The book may be
read without reference to these boxes, the text being complete in itself.
Only readers interested in gaining deeper understanding need apply
themselves to the boxes and this they may do either while reading the
text or, if preferred, treat them as appendices to be read separately.
Iimagine that most readers interested primarily in the historical aspect
of the subject will be happy with the basic text, while students, in
particular, should find the additional insight provided by these boxes of
value. I should nevertheless emphasize that the book is not, in any
sense, to be seen as a substitute for the various standard texts on semi-
conductor physics and devices but rather as complementary to them,
serving toprovide a human slant to much that is otherwise purely tech-
nical. Ihope and believe that many students will find this background
information extremely helpful in satisfying their natural curiosity about
how and why things came to pass and help them to appreciate the
nature of the process of device development. Being a human activity, it
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Preface
should preferably be understood in that context, complete with all its
human foibles.
The approach I have adopted throughout is essentially an interdiscip-
linary one. I have tried always to set device development in the context
of relevant applications, providing, for instance, a fairly thorough
account of the development of optical fibres by way of introduction to
long wavelength semiconductor lasers and photodetectors. I have,
similarly, outlined several applications of semiconductor power devices
before describing the relevant devices. In all cases, the technical mater-
ial is presented in terms of the relevant timescale and I have devoted
considerable attention to the importance of semiconductor materials,
their development in response to device demands and the vital cross-
links with semiconductor physics. All three strands are well represented
and can only be properly understood as a trinity. The book should
therefore be of interest to physicists, electrical engineers, and to mater-
ials specialists, alike. Indeed, if I have been able to impart the essential
message that real human activities, such as this, inevitably cross ped-
agogic boundaries, I shall be well-satisfied. It is clearly apparent that,
without these interdisciplinary interactions, the electronics industry
would not be where it is today and it would be well that its future work-
force (i.e., today’s students) should start their careers with an adequate
understanding of this essential truth. While it is common to present
scientific learning, at both School and University levels, in tidy and
coherent packages, the real world shows little respect for such neat
subdivisions—the successful inventor or entrepreneur must frequently
demonstrate powers of imagination that transcend conventional
boundaries.
Anyone familiar with the subject of semiconductor physics or device
development will appreciate that an account of their history, contained
within a book of modest size, must inevitably be highly selective, and
I make no apology for the fact that my own account lays itself wide
open to such criticism. As Norman Davies remarked, in the preface to
his (relatively thick!) work Europe—A History: ‘This volume—is only one
from an almost infinite number of histories of Europe that could be
written. It is the view of one pair of eyes, filtered by one brain and
translated by one pen.’
Apart form the fact that I typedmy thoughts directly onto my com-
puter, I could make an identical statement here. This book represents
one person’s view of the semiconductor story. Its emphases are my
own, based on my own involvement and inevitably coloured by my own
experiences—and prejudices. But I certainly believe it to represent one
history and one which I hope can be read with much enjoyment.
Should others wish to write theirhistories, I shall be delighted to read
them with equal enjoyment, secure in the knowledge that I may possibly
have stimulated them to improve on my prototype.
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