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It is 50 years since the transistor was announced by Bell Lboratories. This article recounts the author’s experiences wi th transistors and their applications in the early years o f what has been called the transistor revolution. In t h e j r s t f e w years there was a chronic shortage of transistors. Early applications included computers, which ofired the promise $providing data on the reliability o f tvansistors used in relatively large numbers under well-controlled conditions. Other work soon showed that transistors could replace valves in such applications as nuclear research instrumentation. W h e n eventually transistors becamejeely available, they quickly superseded valves in most electronic applications.

ell Laboratories first observed transistor action in December 1947. Their first public demon- stration of point-contact transistors in opera- tion was given in Washington at the Library

Fig. 1 Construction of a Bell point-contact transistor*

of Congress in the sunmer of 1948. Among those who witnessed this demonstrahon was at least one person from Britain, Brian Cakck, who was then in Washington with the British Joint Services Mission.

My own interest in transistors was kindled by a paper presented in April 1951 by James and Wells ofthe GEC Research Laboratories at Wembleyl . They described American work and reported the successful operation of a rad0 receiver incorporating seven transistors and delivering 50 mW output.

In what follows, I shall not attempt a balanced review of early transistor development in the UK. I shall instead try to describe my experience as a member of the Harwell Electronics Division during the early years of the transistor revolution.

The Bell Labs Symposium

In August 1951, a senior member of Hanvell staff, visiting the USA, heard that Bell Labs were going to hold a discussion meeting on transistor applications in September. He strongly recommended British involvement.

The Director of Harwell, Sir John Cockcroft, wrote to his friend Dr. Mewyn Kelly, a t Bell Labs, asking that 1 should attend the meeting. As a result, the British Joint Services Mission (BJSM) in Waslngton received from Bell formal invitations for me and for J. E Gittings, who was a member ofBJSM. Both invitations were subject to rmlitary clearance. The Ministry of Supply then cabled their Washington representative, insisting on the inclusion of George Kng, of Standard Telephones Laboratories, as representing a British Government Prime Contractor, even if this would involve dropping Gittings or myself. Fortunately, the BJSM succeeded in getting all three of us cleared by

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the US Army General Staff, and we all went to the Bell Symposium.

Meanwhile, Cockcroft himself visited Bell Labs and made a private arrangement with Dr. Kelly for me to spend a week there after the symposium and for me to take some transistors home with me afterwards.

Everyone attending the symposium was given a reading list in advance. At the symposium we were each given a book 50 mm thick, weighing almost 2 kg, which surmnarised the material to be presented. There were about 400 people there, out of 2500 who had applied. I believe that the three of us were the only non-Americans present.

Bell had done an impressive job in transistor circuit development for a great variety of applications: amp lifiers, oscdlators, modulators, counters, an optical encoder and even a computer of sorts. Nearly all the work had been done with point-contact transistors.

Fig. 1 shows haw the Bell point-contact transistor was constructed’. The two points, separated by a distance in the range 20-100 pm, were pressed against the surface of the germanium. To obtain effective transistor action, the contacts had to be ‘formed’ by passing pulses of current through them. After forming, the point-contact transistors showed a current gain of about 2 between emitter and collector. This produced a negative-resistance characteristic which was usefd in digital circuits. However, it could cause instability problems in linear amplifiers.

Junction transistors were better understood theoreti- cally, and seemed more promising than point-contact transistors for linear amplification, but Bell had found them appallingly difficult to make.

Discussions with Bell staff

In the week folbwing the symposium, Bob Wallace told me how theirp-n-p junction transistors were made. During the growth of the germanium crystal they changed the doimnant impurity in the germanium melt fromy to n and then quickly back again to p-type, thus growing a thin n-type layer in the predominantly

Fig. 2 Early Bell point-contact transistor

p-type crystal. The thickness of ths n-type base region was typically 25 pm.

The grown crystal was cut longitudnally into thin strips, the surfaces of which were then probed to find the edge of the n-type base region. To make the base connection, a fine gold wire was bonded to ths edge. Since this region was bounded by two junctions only about 25 pm apart, the bonding was an extremely delicate operation. Often the bond would bridge one of the junctions.

Wallace told me that his original junction transistor pape? had been written on the basis of the measured properties of a single transistor. The parameters of a few others had been added at the proof stage. Another symposium paper, on a two-stage amplifier, had been written on the basis of just two junction transistors, both with very poor characteristics. So even Bell were desparately short of junction transistors.

Wallace showed me his current stock of about a dozen junction transistors. He allowed me to take one,

on a very unofficial basis. Later that week, when I was with someone else,

a man put hs head round the door and said ‘The boys from General Electric are here. They are going to tell us how they make transistor junctions by alloying.’ These two sentences conveyed a lot of valuable information. In fact, alloying the emitter and collector to opposite sides of a thin semiconductor wafer overcame the difficulty of malung the base connection, and was to become the accepted way of malung junction transistors for the next few years.

Early work in the UK

Fig. 3 Early Bell junction transistor3 I returned to the UK with three Bell point-contact

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Fig. 4

transistors (Fig. 2), the one junction transistor which Wdace had given me (Fig. 3), and a few p-n junction &odes.

For months these devices were our sole basis for transistor circuit development. They &d, however, enable David Florida and Jim Stephen to set up systems at Harwell for measuring transistor parameters4. Ths capabhty encouraged people to give us early transistors for evaluation.

The performance of our sole junction transistor was impressive. It gave us a taste of what might be, even though there seemed few prospects of obtaining any more. However, the circumstances in whch I had acquired thus transistor made us cautious about publishing information about it.

In October 1951 B d Shockley visited England and lectured at the IEE on the Bell transistor programme. Later, on the 13th and 14th of October, he took part in a conference at Buckland House, a stately home near

GE (US) point-contact transistor

Harwell. Here the main speakers were Shockley, myself and Albert Smales (both of Harwell) and A. E Gibson (TRE Malvern). There was a big attendance at both meetings.

One of the organisations represented at Buckland was CVD-Common Valve Development. During the war, the CVD organisation had standardised the valves de- veloped for the three armed services; it was the main avenue by which defence funds went to the valve industry. To do the same for transistors, the CVD Tran- sistor Sub-committee was set up in January 1952 under the chairmanship ofBrian Calhck. Ths committee had repre- sentatives from the govern- ment research establishments and from industry. I represented Harwell. In 1952

the committee met five times. The armed services required their

equipment to operate at tem- peratures up to at least 70OC. Thus is right at the limit of what can be achieved with germanium. CVD therefore placed strong emphasis on supporting the development of silicon technolow. Ths was the correct decision long-term, but, at that time, the shcon transistor seemed a long way into the future. Those of us who did not have to contend with severe environments

felt that our immedate needs could be met with germanium transistors.

Availability of transistors

At the beginning of 1952, Professor E C. Williams, whom I had come to know well during the war, wrote to me from Manchester University. He had done more than anyone else to advance radar circuit design? he had invented the cathode-ray dgital storage tube, had been responsible for its use in the early computer built at Manchester University, and had laid down many of the fundamentals of computer design. He asked me if I could spare him some of the many transistors he thought I must have brought back from the USA. I had to &sappoint h m . Two of the three point-contact transistors I had brought back from Bell had already faded.

Fortunately for us, Cockcrofi received two GE

Fig. 5 STC point-contact transistor

point-contact transistors from Dr. Suits, then Research Director of General Electric (GE) at Schenectady (Fig. 4).

In March 1952, we received two more point-contact tran- sistors from GE (USA) and four from Bell Labs, via CVD. In April, Cockcroft received s i x more development point- contact transistors from GE. In May 1952, 12 Bell point- contact transistors, obtained by BJSM, went to the Royal Radar Establishment and another four came to us. By mid-1952 we were able to buy British point-contact tran- sistors from Standard Tele- phones and Cables (STC) (Fig. 5).

In September 1952, Jim Fisk, then Head of Bell Labs, visited England and presented me with a grown junction transistor. (I don't thmk he

knew that we already had one!)

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Meanwhile, Man- chester University had acquired enough point- contact transis icors to enable E C. Wdhams and Barry Chaiplin to submit to the IEE a paper on the design of trigger circuits using these transistors6.

Wfiams and Chaplin were a powerful com-

transistor coniputrr?’ ‘Yes’, I replied. I-ie said: ’Wcll, w h y

don’t you?’ 1 could think of no

good redson for not doing so, and \vc began to design the etscntial rransistor circuits for a computer. We dccided to base our design round ;I nmgneric drum store Fig. 6 Early Mullard junction transistor

bination; Barry Chaplin probably had longer experience of transistors than anyone else in the UK. He tells me that, as a final-year undergraduate project, he acquired some of the point-contact crystal &odes used in centimetre radar receivers and succeeded in turning some in to point-contact transistors by addmg a pointed phosphor bronze contact as a collector. After forming this contact by mscharging a capacitor through it, he had obtained current gains of 2 and more, between the two point contacts, as early as 1949.

Transistors in computers b

In July 1952 .Lord Halsbury, then Chairman of the National Research & Development Corporation, spoke to Cockcroft about possible support for UK transistor research and development. Cockcroft asked me to talk with ILIalsbury, who told me that he wanted not just printed circuits but also printed &odes and transistors. I felt t h s was a bit ambitious at the time, but suggested that NRDC (National Research and Development Corporation) support for developing a transistor mgjtal computer would stimulate the development of transistors and of their associated circuits, withoui: having to await the development of silicon technololg.

When I reported back to Cockcroft in August 1952, he agreed that it would be desirable for

with multiple movable heads, designed at the National Physical Laboratory. The store had a nominal capacity of 64 kdobytes. Using a smaller drum, loaned by the Royal Radar Establishment, we were able, by June 1953, to report that we could read and write on a magnetic drum using transistor circuits.

By then we were getting point-contact transistors &om GEC (General Electric Company) as well as fiom STC (Fig. 7). However, point-contact transistors were a little too noisy for the first stages of the amplifiers required to read data fiom the magnetic drum7. Here junction transistors were essential. These were stdl very scarce, so the few we had received fiom Phhps were vital. Even so, we felt we were talung quite a risk in assuming that enough junction transistors would be available for the eight read amplifiers.

At about this time, Dr. Shockley again lectured at the IEE. At the end of hs lecture he produced two large cardboard boxes, which turned out to be full of junction transistors. These he proceeded to throw in handfids into the audence. There was a highly undgnified scramble. We managed to grab a few. They turned out to be just usable, though they were outside specification.

Not long afterwards alloyed junction transistors became available &om British sources. Some of these are shown in Fig. 8.

some organisation to sponsor de- velopment of computers using germanium transistors .

In December 1952 Cockcroft visited the Philips Research Labora- tories at Eindhuren and looked at their transistor work. Once again he helped us, for this visit led to the Philips researchers sencling us a few of their experimental junction transistors. Fig. 6 shows a sirmlar transistor supplied to us later by Mullard.

Among the experimental transistor circuits we had operating in the laboratory was a binary shift register, which would recirculate a given binary number for long periods. We showed this to Cockcroft during one of his periodic visits to our laboratory.

He asked ‘Could YOU build a Fig. 7 GEC point-contact transistor

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Fig. 8 Early British Junction Transistors

The main transistor logic circuits we used in our computer were described at an IEE meeting in April 1954’. At the same meeting, Barry Chaplin described the transistor logic elements being worked on by Professor Tom Kdburn’s team at Manchester’.

The transistor computers designed at Manchester and at Harwell were both described in papers presented at the IEE Digital Computer Convention in April 1956“’~”. Each computer used a magnetic drum as the main storage. The Manchester computer was the faster, but needed valves to generate the clock waveforms at 125 kHz and to read and write on the magnetic drum.

The Harwell computer (CADET-ee Fig. 9) used a lower clock G-equency, of 58 kHz, and this enabled us to avoid using any valves. Its slower speed was to some extent offset by the ability to add together up to eight numbers concurrently. It began to operate in February 1955, and came into regular use six months later. We believe that this was the second fully-transistorised computer in the world to be put to use (IBM was first, by a short head).

CADET was built up fioiii a few standardised

dismantled and its performance analy~ed’~.

Other work on transistor circuits

There were, of course, other British organisations working on transistors and their applications. British industry was pushing ahead with the development of junction transistors, and with silicon technolog. At the Royal Radar Establishment at Malvern, Alan Gibson led a team working on semiconductor materials and on the properties of charge carriers, contacts and junctions. At the Post Office Research Station, D o h Hill, John Tdlman was also active. I learned a lot about semiconductors from both of them.

The general interest in transistors became enormous. Any IEE meeting with the word ‘transistor’ in its title could be guaranteed a full house. At an IEE discussion meeting in December 1953, entitled ‘Will transistors oust receiving valves?’ there was standing room only and people were sitting in the gangways.

Apart from the computer, we at Harwell were using transistors in electronic devices connected with the nuclear energy programme. Early in 1952 we built a portable gamma radiation monitor, using two point-

Fig. 9 The Harwell all-transistor computer (CADET)

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Fig. 10 Portable Geiger counter using transistors (1952)

contact transistors (Fig. 10). One transistor was used as a transformer-coupled oscillator to generate the high-voltage supply for a Geiger-Muller counter. The second transistor was triggered by the pulses generated by the counter, producing a current proportional to pulse rate. A wide-ranging IEE paper by Frankhn and James14 described this and several other transistorised nuclear instruments.

By 1956, Barry Chaplin and his colleague Alwyn Owens had joined us from

on the same face ofthe crystal. It was not untiljunction technology developed to the stage where the emitter and collector could both be placed on the same face of the semiconductor crystal that the speed of junction transistors began to surpass that of point-contact transistors.

As well as counting circuits, Barry Chaplin's team developed sensitive, but stable, DC amplifier^'^-'^, and wide-band amplifiers'9. However, they were not able

Manchester Ur&ersity. They formed the nucleus of a group charged with arweII applying transistors to the varied needs for eletztronics in the UK C uter wa Nuclear Energy programme. A torrent of papers followed, most of which wen: presented at the IEE. These included a paper describing a p l se counting circuit with a time rt:solution of 400 ns15. This still used point-contact transistors; the best that could be achieved at the time with junction transistors was five times slower".

At the time, junction transistors were made with the emitter and collector placed on opposite sides of a thin oscilloscope to senliconductor wafer, through which the injected to 300 MHz" .

to devise transistor DC amplifiers able to measure the very small chrect currents, of the order of A, produced by the ionisation chambers in personal radiation dosimeters. Here the electrometer valve was to remain supreme for many years more.

Avalanche transistors

A very interesting development was the use of avalanche multiplication in a relatively slow junction transistor to generate nanosecond pulses2". This led to the design of a sampling attachment for a normal cathode-ray oscilloscope which enabled the

display recurrent waveforms &om DC

minority carriers diffused. It was difficult to make the This was the subject of a very convincing diffusion time as short as the time taken for carriers in demonstration at the IEE. A large oscilloscope was point-contact transistors to drift from emitter to placed on the lecturers' bench and a transmission line, collector, both electrodes being located close together consisting oftwo parallel copper tubes 14 feet long, was

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laid at a slight downward slope from the bench onto the middle aisle of the lecture room. Nanosecond pulses were launched down tlus line and could be reflected at a short-circuit. The reflected pulses were &splayed along a range trace on the oscdloscope.

Initially the line was short-circuited by a copper sphere, placed at the hghest point. The cathode-ray &splay showed the initial nanosecond pulse produced by the avalanche transistor, together with the delayed blip representing the pulse reflected &om the short- circuit at the beginning of the transmission line. When the sphere was released, and rolled slowly down the line, the reflection delay increased, and the blip moved steadily across the screen at a rate of about one nanosecond per foot. The blip finally reversed polarity and came to rest as the sphere fell off the end of the transmission line and trundled up the aisle.

With the very fast transistor circuits avadable today, such a demonstration would not be surprising, but in the days when transistor cut-off kequencies were limited to a few megahertz it was truly remarkable.

Conclusion

What I have described was an exciting time, but it was only the beginning. Stdl to come were sdicon transis- tors, field-effect transistors, microcircuits, large-scale integration, microprocessors and personal computers. Many years of fascinating development lay ahead. It is a privilege to have been part of it.

Acknowledgments

From what I have said, it will be clear that we benefited greatly from the interest and support of Sir John Cockcrofi. He was responsible for a major part of the UK nuclear energy programme, involving many thousands of people. He had many taxing problems to address and endless demands on hs time, so we were very fortunate.

This paper is based on one whch I presented at a Discussion Meeting on ‘Transistors: the context of their discovery, development and use 193C-1960’ at the Institution of Electrical Engineers held on 16th December 1997. In its preparation I had valuable help from Brian Callick, Barry Chaplin, James Stephen and several others.

I am gratefd to James Stephen for providng me with examples of early transistors, and to the UK Atomic Energy Authority for permission to use Figures 9 and 10.

References

1 JAMES, E. G., and WELLS, G. M.: ‘Crystal triodes’. Paper read before the South Midland Section of the Brit. I= on 11th April 1951

2 RYDER, R. M., and KIRCHER, R. J.: ‘Some circuit aspects of the transistor’, Bell Syst. Tech. J , July 1949, 28, pp.367-40 1

3 WALLACE, R. L., and PIETENPOL, W. J.: ‘Some circuit properties and applications of n-p-n transistors’, Bell Syst. l kh . J . , July 1951, 30, pp.753-767

4 COOKE-YARBOROUGH, E. H., FLORIDA, C. D., and STEPHEN, J. H.: ‘The measurement of the smal- signal characteristics of transistors’, Proc. IEE, September

5 WILLIAMS, E C.: ‘Introduction to circuit techniques for ra&olocation’,J IEE, 1946, Pt. IIIA, (93)

6 WILLIAMS, E C., and CHAPLIN, G. B. B.: ‘A method of designing transistor trigger circuits’, Proc. IEE, 1953, 100, Pt. 111, p.228

7 STEPHEN, J. H., and COOKE-YARBOROUGH, E. H.: ‘An interleaved-digit magnetic drum store for a transistor digital computer’, Proc. IEE, 1956, 103, Pt. B Supplement 3, pp.382-389

8 COOKE-YARBOROUGH, E. H.: ‘A versatile transistor circuit’, Pvoc. IEE, September 1954, 101, Pt. 111, (73),

9 CHAPLIN, G. B. B.: ‘The transistor regenerative amplifier as a computing element’, Proc. IEE, September 1954, 101, Pt. 111, (73), pp.298-307

10 COOKE-YARBOROUGH, E. H., BARNES, R. C. M., STEPHEN, J., and HOWELLS, G. A,: ‘A transistor &gital computer’, Pvoc. IEE, 1956, 103, Pt. €3, pp.364-370

11 KILBURN, T., GRIMSDALE, R . L., and WEBB, D. C.: ‘A transistor dgital computer with a magnetic-drum store’, Proc. IEE, 1956, 103, Pt. B, pp.390406

12 COOKI-YARBOROUGH, E. H., andBARNES, R. C. M.: ‘Rapid methods of ascertaining whether the activity of a weak radioactive sample exceeds a predetermined level’, Proc. IEE, March 1961, 108, Pt. B, (38), pp.153-166

13 BARNES, R . C. M., and STEPHEN, J. H.: ‘Operating experience with a transistor mgital computer’, Proc. IEE,

14 FRANIUIN, E., and JAMES, J. B.: ‘The application of transistors to the trigger, ratemeter and power-supply circuits of radiation monitors’, P m . IEE, July 1956, 103,

15 CHAPLIN, G. B. B.: ‘A point-contact transistor scaling circuit with 0.4 microsecond resolution’, Proc. IEE, July

16 CHAPLIN, G. B. B., and OWENS, A. R.: ‘A Junction- transistor scaling circuit with 2-microsecond resolution’, Proc. IEE, July 1956, 103, Pt. B, (lo), pp.510-515

t 7 CHAPLIN, G. B. B., and OWENS, A. R.: ‘A transistor high-gain chopper-type D C amplifier’, Proc. IEE, May

18 CHAPLIN, G. B. B., and OWENS, A. R.: ‘Some transis- tor input stages for hgh-gain D C amplifiers’, Pvoc. IEE, May 1958, 105, Pt. B, (21), pp.249-257

19 CHAPLIN, G. B. B., CANDY C. J. N., and COLE, A. J.: ‘Transistor stages for wide-band amplifiers’, R o c . IEE, 1959,

1954, 101, Pt. 111, (73), pp.288-293

pp.281-287

1959, 106, Pt. B, pp.222-228

Pt. B, (lo), pp.497-504

1956, 103, Pt. B, (IO), pp.505-509

1958, 105, Pt. B, (21), pp.258-266

106, Pt. B, pp.762-772 20 CHAPLIN, G. B. B., and OWENS, A. R.: ‘A method of

designing avalanche transistor trigger circuits’, Proc. IEE, 1959,106, Pt. B, pp.806-814

21 CHAPLIN, G. B. B., OWENS, A. R., and COLE, A. J.: ‘A sensitive transistor .oscillograph with D C to 300 Mc/s response’, Proc. IEE, 1959, 106, Pt. B, pp.815-823

0 IEE: 1998

The author is an IEE Fellow and a member of the Fellowship of Engineering.

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