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The Unsung Inventor Who Chased the LED Rainbow

Stroll by half a soccer subject’s value of low partitions, submitting cupboards, and desks. Word the curved mirrors hanging from the ceiling, the higher to view the maze of engineers, technicians, and help employees of the event laboratory. Shrug while you spot the plastic taped over just a few of the mirrors to impede that view.

Go to the center of this labyrinth and there discover M. George Craford, R&D supervisor for the optoelectronics division of Hewlett-Packard Co., San Jose, Calif. Sitting in his shirtsleeves at an industrial beige metallic desk piled with papers, amid dented bookcases, fitness center bag within the nook, he doesn’t appear to be anyone’s definition of a star engineer.

Appearances are deceiving.

This text was first revealed as “M. George Craford.” It appeared within the February 1995 problem of IEEE Spectrum. A PDF model is on the market on IEEE Xplore. The pictures appeared within the unique print model.

“Have a look round throughout the subsequent few days,” suggested Nick Holonyak Jr., the John Bardeen professor {of electrical} and laptop engineering and physics on the College of Illinois, Urbana, and the creator of the primary LEDs. “Each yellow light-emitting diode you see—that’s George’s work.”

Holonyak sees Craford as an iceberg—exhibiting a small tip however leaving an incredible breadth and depth unseen. Certainly, Craford does show to be filled with surprises—the fitness center bag, for instance. He skips lunch for exercises in HP’s basement fitness center, he stated, to get in form for his subsequent journey, no matter that is likely to be. His newest was climbing the Grand Teton; others have ranged from parachute leaping to whitewater canoeing.

His greatest journey, although, has been some 30 years of analysis into light-emitting diodes.

The decision of area

When Craford started his training for a technical profession, inthe Fifties, LEDs had but to be invented. It was the journey of outer area that referred to as to him.

The Iowa farm boy was launched to science by Illa Podendorf, an creator of youngsters’s science books and a household buddy who saved the younger Craford equipped with texts that suited his pursuits. He dabbled in astronomy and have become a member of the American Affiliation of Variable Star Observers. He constructed rockets. He carried out chemistry experiments, one time, he recollects with glee, producing an explosion that cracked a window in his dwelling laboratory. When the time got here, in 1957, to choose a school and a significant, he determined to pursue area science, and chosen the College of Iowa, in Iowa Metropolis, as a result of area pioneer James Van Allen was a physics professor there.

Very important statistics


Magnus George Craford

Date of beginning

Dec. 29, 1938


Sioux Metropolis, Iowa


185 cm


Spouse, Carol; two grownup sons, David and Stephen


BA in physics, College of Iowa, 1961; MS and PhD in physics, College of Illinois, 1963 and 1967

First job

Weeding soybean fields

First electronics job

Analyzing satellite tv for pc knowledge from area


About 10

Individuals most revered

Explorer and adventurer Sir Richard Burton, photographer Galen Rowell, Nobel­ Prize winner John Bardeen, LED pioneer Nick Holonyak Jr.

Most up-to-date guide learn

The Allure College

Favourite guide

Day of the Jackal

Favourite periodicals

Scientific American, Sports activities Illustrated, Nationwide Geographic, Enterprise Week

Favourite music

String quartets

Favourite composers

Mozart, Beethoven


“I don’t use one”

Favourite TV present

“NYPD Blue”

Favourite meals

Thai, Chinese language

Favourite restaurant

Eating room at San Francisco’s Ritz Carlton Resort

Favourite motion pictures

Bridge on the River Kwai, Butch Cassidy and the Sundance Child, The Lion in Winter

Leisure exercise

Mountain climbing, strolling, snow snowboarding, bicycling, tennis, and, most just lately, technical mountaineering.


Sable Wagon (an organization automobile)

Pet peeves

“Those that work for me who don’t come to me with little issues, which fester and switch into large ones.”

Organizational membership

IEEE, Society for Info Show

Favourite awards

Nationwide Academy of Engineering, IEEE Fellow, IEEE Morris N. Liebmann Memorial Award; however “the whole lot you do is a crew factor, so I’ve blended emotions about awards.”

Because the area race heated up, Craford’s curiosity in area science waned, despite a summer season job analyzing knowledge returned from the primary satellites. He had discovered a bit about semiconductors, an rising subject, and Van Allen pointed him towards the solid-state physics program on the College of Illinois, the place Craford studied first for a grasp’s diploma, then a PhD.

The glowing Dewar

For his doctoral thesis, Craford started investigating tunneling results in Josephson junctions. He had invested a number of years in that analysis when Holonyak, a pioneer in seen lasers and light-emitting diodes, left his place at Basic Electrical Co. and joined the Illinois college. Craford met him at a seminar, the place Holonyak was ex­plaining his work in LEDs. Recalled Craford: “He had a bit of LED—only a crimson speck—and he plunged it right into a Dewar of liquid nitrogen, and it lit up the entire flask with a vivid crimson gentle.”

Entranced, Craford instantly spoke to his thesis adviser about switching, a reasonably uncommon proposal, because it concerned dropping years of labor. “My thesis adviser was good about it; he had been spending much less time across the lab these days, and Holonyak was build up a gaggle, so he was keen to take me on.”

Craford believes he persuaded the laser pioneer to simply accept him, the senior man recollects issues in another way.

Craford’s adviser “was working for U.S. Congress,” Holonyak stated, “and he instructed me, ‘I’ve bought this good pupil, however I’m busy with politics, and the whole lot we do somebody publishes forward of me. I can’t take excellent care of him. I’d such as you to choose him up.”’

Nevertheless it occurred, Craford’s profession path was lastly set—and the lure of the glowing crimson Dewar by no means dimmed.

Holonyak was rising gallium arsenide phosphide and utilizing it efficiently to get vivid LEDs and lasers. He assigned his new advisee the job of borrowing some high-pressure gear for experiments with the fabric. After discovering a professor with a strain chamber he was keen to lend, Craford arrange work within the basement of the supplies analysis constructing. He would carry GaAsP samples from the lab to the supplies analysis basement, cool them in liquid nitrogen, enhance the strain to review the variation of resistivity, and see surprising results.

“Simply cooling some samples would trigger the resistance to go up a number of instances. However add strain, and they’d go up a number of orders of magnitude,” Craford stated. “We couldn’t work out why.”

Finally, Craford and a co-worker, Greg Stillman, decided that variations in resistance had been associated not solely to strain but additionally to gentle shining on the samples. “If you cooled a pattern after which shone the sunshine on it, the resistance went down—means down—and stayed that means for hours or days so long as the pattern was saved at low temperature, an impact referred to as persistent photoconductivity.” Additional analysis confirmed that it occurred in samples doped with sulfur however not tellurium. Craford and Stillman every had sufficient materials for a thesis and for a paper revealed in the Bodily Assessment.

The phenomenon appeared to have little sensible use, and Craford put it out of his thoughts, till a number of years later when researchers at Bell Laboratories discovered it in gallium aluminum arsenide. “Bell Labs referred to as it the DX Middle, which was catchy, studied it intensively, and over time, many papers have been revealed on it by numerous teams,” Craford stated. Holonyak’s group’s contribution was largely forgotten.

“He doesn’t promote himself,” Holonyak stated of Craford, “and generally this troubles me about George; I’d prefer to get him to be extra ahead about the truth that he has finished one thing.”

Transfer to Monsanto

After receiving his PhD, Craford had a number of job gives. Essentially the most fascinating had been from Bell Laboratories and the Monsanto Co. Each had been engaged on LEDs, however Monsanto researchers had been specializing in gallium arsenide phosphide, Bell researchers on gallium phosphide. Monsanto’s analysis operation was much less well-known than Bell Labs’ and taking the Monsanto job appeared to be a little bit of a danger. However Craford, like his hero—adventurer Richard Burton, who spent years in search of the supply of the Nile—has little resistance to selecting the much less well-trodden path.

Apart from, “Gallium phosphide simply didn’t appear proper,” stated Craford, “however who knew?”

In his early days at Monsanto, Craford experimented with each lasers and LEDs. He centered on LEDs full time when it turned clear that the defects he and his group had been encountering in rising GaAsP on GaAs substrates wouldn’t allow fabrication of aggressive lasers.

[He] didn’t toot his personal horn. “When George [Craford] revealed the work, he put the names of the fellows he had rising crystals and placing the issues collectively forward of his identify.”
—Nick Holonyak

The breakthrough that allowed Craford and his crew to transcend Holonyak’s crimson LEDs to create very vivid orange, yellow, and inexperienced LEDs was prompted, sarcastically, by Bell Labs. A Bell researcher who gave a seminar at Monsanto talked about the usage of nitrogen doping to make oblique semiconductors act extra like direct ones. Direct semiconductors are often higher than oblique for LEDs, Craford defined, however the oblique kind nonetheless must be used due to band gaps huge sufficient to offer off gentle within the inexperienced, yellow, and orange a part of the spectrum. The Bell researcher indicated that the labs had had appreciable success with Zn-O doping of gallium phosphide and a few success with nitrogen doping of gallium phosphide. Bell Labs, nonetheless, had revealed early experimental work suggesting that nitrogen didn’t enhance GaAsP LEDs.

Man holding panel with 6 by 3 array of LEDs over his head with both hands

Nonetheless, Craford believed within the promise of nitrogen doping reasonably than the revealed outcomes. “We determined that we might develop higher crystal and the experiment would work for us,” he stated.

A small crew of individuals at Monsanto did make it work. Right now, some 25 years later, these nitrogen-doped GaAsP LEDs nonetheless type a big proportion—some 5-10 billion—of the 20-30 billion LEDs bought yearly on the earth as we speak.

“The preliminary response was, ‘Wow, that’s nice, however our clients are very pleased with crimson LEDs. Who wants different colours?’”

—George Craford

Once more, Holonyak complains, Craford didn’t toot his personal horn. “When George revealed the work, he put the names of the fellows he had rising crystals and placing the issues collectively forward of his identify.”

His friends, nonetheless, have acknowledged Craford because the artistic pressure behind yellow LEDs, and he was just lately made a member of the Nationwide Academy of Engineering to honor this work.

Craford recollects that the brand new palette of LED colours took a while to catch on. “The preliminary response,” he stated, “was, ‘Wow, that’s nice, however our clients are very pleased with crimson LEDs. Who wants different colours?’”

Westward ho!

After the LED work was revealed, a Monsanto reorganization bumped Craford up from the lab bench to supervisor of superior expertise. Considered one of his first duties was to pick out researchers to be laid off. He recollects this as one of many hardest jobs of his life, however subsequently discovered that he favored administration. “You might have extra selection; you have got extra issues that you’re semi-competent in, although you pay the value of turning into rather a lot much less competent in anybody factor,” he instructed
IEEE Spectrum.

Quickly, in 1974, he was bumped up once more to expertise director, and moved from Monsanto’s company headquarters in St. Louis to its electronics division headquarters in Palo Alto, Calif. Craford was accountable for analysis teams growing expertise for 3 divisions in Palo Alto, St. Louis, and St. Peters, Mo. One handled compound semiconductors, one other with LEDs, and the third with silicon supplies. He held the publish till 1979.

At the same time as a supervisor, he remained a “scientist to the enamel,” stated David Russell, Monsanto’s director of selling throughout Craford’s tenure as expertise director. “He’s a pure mental scientist to a fault for an previous peddler like me.”

Although all the time the scientist, Craford additionally has a popularity for relating nicely to individuals. “George is ready to categorical sophisticated technical points in a means that every one of us can perceive,” stated James Leising, product growth supervisor for HP’s optoelectronics division.

Leising recalled that when he was manufacturing engineering supervisor, a place that often put him in battle with the analysis group, “George and I had been all the time in a position to work out the conflicts and stroll away pals. That wasn’t all the time the case with others in his place.” One time specifically, Leising recalled, Craford satisfied the manufacturing group of the necessity for exact management of its processes by graphically demonstrating the intricacies of the best way semiconductor crystals match upon each other.

As an govt, Craford takes credit score for no particular person achievements at Monsanto throughout that point, however stated, “I used to be happy with the truth that, by some means, we managed to be worldwide opponents in all our companies.” Even so, Monsanto determined to dump its optoelectronics enterprise and supplied Craford a job again in St. Louis, the place he would have been answerable for analysis and growth within the firm’s silicon enterprise.

Craford thought of this provide lengthy and onerous. He favored Monsanto; he had a difficult and vital job, full with a giant workplace, oak furnishings, a non-public convention room, and a full-time administrative assistant. However transferring again to St. Louis would finish his romance with these tiny semiconductor lights that would make a Dewar glow, and when the time got here, he simply couldn’t do it.

He did the Silicon Valley stroll: throughout the road to the closest competitor, on this case, Hewlett-Packard Co.

As an alternative, he did the Silicon Valley stroll: throughout the road to the closest competitor, on this case, Hewlett-Packard Co. The one job it might discover that may let him work with LEDs was a giant step down from expertise director—a place as R&D part supervisor, directing fewer than 20 individuals. This meant a minimize in wage and perks, however Craford took it.

The tradition was completely different, to say the least. No extra fancy workplace and personal convention room; at HP Craford will get solely “a cubby, a tin desk, and a tin chair.”

And, he instructed
Spectrum, “I find it irresistible.”

He discovered the HP tradition to be much less political than Monsanto’s, and believes that the dearth of closed places of work promotes collaboration. At HP, he interacts extra with engineers, and there’s a higher sense that the entire group is pulling collectively. It’s extra open and communicative—it must be, with most engineers’ desks merely 1.5 meters aside. “I like the entire model of the place,” he declared.

Now he has moved up, to R&D supervisor of HP’s optoelectronics division, with a bigger group of engineers below him. (He nonetheless has the cubby and metallic desk, nonetheless.)

As a supervisor, Craford sees his position as constructing groups, and judging which sorts of tasks are value specializing in. “I do a fairly good job of staying on the trail between being too conservative and too blue sky,” he instructed
Spectrum. “It will be a nasty factor for an R&D supervisor to say that each undertaking we’ve finished has been profitable, as a result of then you definately’re not taking sufficient probabilities; nonetheless, we do should generate sufficient earnings for the group on what we promote to remain worthwhile.”

Stated Fred Kish, HP R&D undertaking supervisor below Craford: “We have now embarked upon some new areas of analysis that, to some individuals, could have been questionable dangers, however George was keen to attempt.”

Craford walks that path between conservatism and danger in his private life as nicely, though some individuals won’t consider it, given his penchant for adventurous sports activities: skydiving, whitewater canoeing, marathon working, and mountain climbing. These are measured dangers, in line with Craford: ‘‘The Grand Teton is a critical mountain, however my son and I took a rock-climbing course, and we went up with a man who’s an skilled, so it appeared like a manageable danger.”

Holonyak recollects an event when a chunk of crystal formally confined to the Monsanto laboratory was handed to him by Craford on the grounds that an experiment Holonyak was making an attempt was vital. Craford “might have gotten fired for that, however he was keen to gamble.”

“I hope to see the day when LEDs will illuminate not only a Dewar however a room.”

—George Craford

Craford is often known as being an irrepressible asker of questions.

“His strategies of asking questions and taking a look at issues brings individuals within the group to the next degree of pondering, reasoning, and problem-solving,’’ Kish stated.

Holonyak described Craford as “the one man I can tolerate asking me query after query, as a result of he’s actually attempting to know.”

Craford’s group at HP has finished work on a wide range of supplies over the previous 15
years, together with gallium aluminum arsenide for high-brightness crimson LEDs and, extra just lately, aluminum gallium indium phosphide for high-brightness orange and yellow LEDs.

The newest technology of LEDs, Craford stated, might change incandescent lights in lots of functions. One use is for exterior lighting on vehicles, the place the lengthy life and small measurement of LEDs allow automobile designers to mix decrease meeting prices with extra uncommon styling. Site visitors indicators and large-area show indicators are different rising functions. He’s proud that his group’s work has enabled HP to compete with Japanese LED producers and maintain its place as one of many largest sellers of visible-light LEDs on the earth.

Craford has not stopped loving the magic of LEDs. “Seeing them out and used continues to be enjoyable,” he instructed
Spectrum. “After I went to Japan and noticed the LEDs on the Shinkansen [high-speed train), that was a thrill.”

He expects LEDs to go on challenging other forms of lighting and said, “I still hope to see the day when LEDs will illuminate not just a Dewar but a room.”

Editor’s note: George Craford is currently a fellow at Philips LumiLEDs. He got his wish and then some.

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