Morgan Sparks, the man who made the first junction transistor dies aged 91

Morgan Sparks, who invented the junction transistor, the first practical transistor device died on Saturday at his daughter's home in Fullerton, Calif., at the age of 91.

He said of Bell Laboratories approach to introducing the device...."It was quite different from other laboratories. I think AT&T recognized that, as compensation perhaps for their role as a monopoly, they had some obligations. And so the labs were really very open. And, you know, the transistor, it took a few months to get patents filed and things of that nature, and there was a bit of a battle with the military, who wanted to keep it secret. And the lab's attitude prevailed, and it was essentially thrown open. Licensing agreements were offered to anybody in the world."

William Shockley’s theories about p-n junctions had been validated by tests by Richard Haynes in 1948 . Haynes put electrodes on both sides of a thin germanium crystal and took very sensitive measurements of the size and speed of the current. Electricity definitely flowed straight through the crystal. That meant Shockley's vision of a new kind of transistor was theoretically possible..... but fabricating a working junction transistor presented formidable challenges.

Few listened to Bell Labs chemist Gordon Teal who argued that large, single crystals of germanium and silicon would be required as opposed to cutting a sliver from a larger ingot of many crystals

Using a technique developed in 1917 by the Polish chemist Jan Czochralski, Teal , working with engineer John Little suspended a small “seed” crystal of germanium in a crucible of molten germanium and slowly withdrew it, forming a long, narrow, single crystal.

Shockley was later to call this achievement “the most important scientific development in the semiconductor field in the early days.”

But beautiful single crystals are fine but a sandwich transistor (as distinct from point type) needed a sandwich crystal. The outer layers had to be a semiconductor with either too many electrons (known as N-type) or too few (known as P-type), while the inner layer was the opposite.

Morgan Sparks developed Teals crystal growing techniques and fabricated p-n junctions by seeding tiny pellets of impurities into the molten germanium during the crystal-growing process. In April 1950, he and Teal began adding two successive pellets into the melt, the first with a p-type impurity (gallium) and the second n-type (antinomy) , forming n-p-n structures with a thin inner, or base, layer.

Sparks and Teal etched away the surface of the outside layers, leaving a tiny bit of P-type crystal protruding. They attached a fine electrode-creating a circuit the way Shockley had suggested. 58 years ago on April 12, 1950, they tested what they had built. Without a doubt, more current came out of the sandwich than went in. They had a tiny working amplifier.

A year later, after refining the crystal growing proces such “grown-junction transistors” surpassed the best point-contact transistors in performance. Bell Labs announced this advance on July 4th, 1951 in a press conference featuring Shockley. (Sparks, Morgan and Teal, Gordon K. “Method of Making P-N Junctions in Semiconductor Materials,” U. S. Patent 2,631,356 (Filed June 15, 1950. Issued March 17, 1953)

In 1954, Bell Labs and Texas Instruments fabricated the first successful silicon transistors. The following year Bell Labs chemist Morris Tanenbaum developed the first silicon junction transistor using diffusion of trace impurities to grow ultra-thin base layers less than one micrometer thick.

The rest, as they say ... is history.