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The Revolution In Your Pocket
FIFTY YEARS AGO A TRANSISTOR RADIO CALLED THE TR1 STARTED THE REMAKING OF THE WORLD BY SEMICONDUCTORS
Fall 2004 | Volume 20, Issue 2
HALF A CENTURY AGO THIS AUTUMN TWO SMALL COMPANIES, working together, unveiled the world’s first transistor radio. It was called the Regency TR1. It introduced the revolutionary technology of the transistor to the general public, and it began the spread of all the miniaturized, battery-operated electronic devices that surround us today.
The companies were Texas Instruments and Industrial Development Engineering Associates. TI made instrumentation for the oil industry and locating devices for the Navy; IDEA mainly built home TV antenna boosters, many carrying the Sears Silvertone brand name. But TI wanted to grow from a $20 million company into a $200 million one, and IDEA wanted to get into new product areas. The unlikely pairing of the two companies created, within a very short time, a product that in its styling, its circuit design, its manufacturing technology, and, above all, its use of miniaturized components pointed the way to the future.
Texas Instruments started work on a pocket radio in the spring of 1954, but the seeds of the idea had been planted three years earlier. In 1951 Pat Haggerty, TI’s vice president, decided to bet the company by licensing the new technology of the transistor from Bell Laboratories, which had invented it. Haggerty had the vision to see that the little solid-state device would eventually replace the millions of vacuum tubes then at the heart of the fast-growing electronics industry. By 1954 he was eager to get in at the start by establishing a high-volume, high-profile consumer market before anyone else did. He chose the portable AM radio.
The transistor had been invented at Bell Labs by John Bardeen, Walter Brattain, and William Shockley, and it was announced to the world on June 30, 1948. It was made, in the beginning, of germanium, an element whose pure crystalline form is a very good insulator. “Doping” germanium with an impurity could turn it from an insulator into a feeble conductor of electrons, or semiconductor. Depending on the element it was doped with, it either had an excess of electrons and was called N-type (for negative ) or had a deficit of electrons and was called P-type. If you placed the two types next to each other, you got a P-N junction diode, which would pass electric current in only one direction.
You got a junction transistor (which quickly succeeded the crude original point-contact transistor) by sandwiching three doped regions of germanium to create back-to-back junctions, either N-P-N or P-N-P. This sandwich would block current both ways until a small current was applied to the central region, called the base; then the transistor structure would allow a much larger current to flow through the sandwich as a whole. That meant it could be used as either a switch or an amplifier, the current applied to the base either turning the whole thing on and off as a switch or making it act as an amplifier, with a modest current to the base allowing a corresponding larger current to flow through the whole. Thus a tiny chip of germanium 14 (or, later, silicon) could do the same work previously done by a large, hot vacuum tube.
Bell Labs’ first transistors were extremely delicate devices, made by contacting a very small chip of N-type germanium crystal with wires spaced a few thousandths of an inch apart through a P-type layer. Dropping one could destroy it, and the contact areas were easily contaminated.
In 1950 Bell’s scientists invented a way of “growing” a junction transistor by pulling a “seed” crystal from a crucible of molten germanium and “doping” it with small amounts of the impurity elements as it came out. Bell Labs attached a fine gold wire containing an impurity element to the base area of the transistor by welding it with a quick high-current pulse. The process held promise, but it was so difficult to control that at the outset only one in 20 devices worked.
Executives at Bell Labs figured that the technology would develop much faster if a lot more people got involved with it, so in 1951 they decided to license it to anyone interested for $25,000. Haggerty paid the fee, and Texas Instruments became one of more than two dozen licensees. It was well known that germanium transistors worked poorly at frequencies above 100 kHz when temperatures exceeded 167 de- grées, so they would have little use in large industrial and military markets. With that in mind, Haggerty hired Gordon Teal, who had helped develop the techniques for growing semiconductor crystals at Bell Labs, and the physical chemist Willis Adcock to begin work at TI on semiconductors made of silicon. Silicon is an element with the same number of electrons in its outer shell as germanium and therefore has very similar properties, but it worked better at high temperatures. By 1954 TI had made much more progress with silicon than its rivals had thought possible. In May 1954 the company surprised the industry by announcing that it had made silicon transistors that worked.
Now Haggerty was impatient to develop a mass market. In the five years since the first crude prototype had been unveiled, only about a million germanium transistors had been fabricated by the entire industry. They had gone into a small number of military and commercial applications; the only consumer products were a few hearing-aid amplifiers, whose high price was justified by a savings in batteries, which were very expensive for power-thirsty vacuum-tube hearing aids.