HomeTechnologyThe Unsung Inventor Who Chased the LED Rainbow

The Unsung Inventor Who Chased the LED Rainbow

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

Go to the guts 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 steel desk piled with papers, amid dented bookcases, gymnasium bag within the nook, he doesn’t seem like anyone’s definition of a star engineer.

Appearances are deceiving.

This text was first printed as “M. George Craford.” It appeared within the February 1995 difficulty of IEEE Spectrum. A PDF model is out there on IEEE Xplore. The images appeared within the authentic print model.

“Have a look round through the subsequent few days,” suggested Nick Holonyak Jr., the John Bardeen professor {of electrical} and pc 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 gymnasium bag, for instance. He skips lunch for exercises in HP’s basement gymnasium, he mentioned, to get in form for his subsequent journey, no matter that may 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 house

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

The Iowa farm boy was launched to science by Illa Podendorf, an writer of kids’s science books and a household buddy who saved the younger Craford provided 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 residence laboratory. When the time got here, in 1957, to choose a university and a serious, he determined to pursue house science, and chosen the College of Iowa, in Iowa Metropolis, as a result of house pioneer James Van Allen was a physics professor there.

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 information from house


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 Attraction Faculty

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 Lodge

Favourite motion pictures

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

Leisure exercise

Mountaineering, strolling, snow snowboarding, bicycling, tennis, and, most lately, technical mountaineering.


Sable Wagon (an organization automotive)

Pet peeves

“Those who 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 “every part you do is a staff factor, so I’ve combined emotions about awards.”

Because the house race heated up, Craford’s curiosity in house science waned, regardless of a summer time job analyzing information returned from the primary satellites. He had discovered a bit about semiconductors, an rising discipline, 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 Common Electrical Co. and joined the Illinois school. Craford met him at a seminar, the place Holonyak was ex­plaining his work in LEDs. Recalled Craford: “He had slightly LED—only a pink speck—and he plunged it right into a Dewar of liquid nitrogen, and it lit up the entire flask with a vivid pink 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 increase a bunch, so he was prepared to take me on.”

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

Craford’s adviser “was operating for U.S. Congress,” Holonyak mentioned, “and he instructed me, ‘I’ve obtained this good scholar, however I’m busy with politics, and every part 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 pink 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 tools for experiments with the fabric. After discovering a professor with a strain chamber he was prepared 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 occasions. However add strain, and they might go up a number of orders of magnitude,” Craford mentioned. “We couldn’t work out why.”

Ultimately, Craford and a co-worker, Greg Stillman, decided that variations in resistance had been associated not solely to strain but in addition to gentle shining on the samples. “While you cooled a pattern after which shone the sunshine on it, the resistance went down—manner down—and stayed that manner for hours or days so long as the pattern was saved at low temperature, an impact known 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 printed 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 known as it the DX Heart, which was catchy, studied it intensively, and over time, many papers have been printed on it by varied teams,” Craford mentioned. Holonyak’s group’s contribution was largely forgotten.

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

Transfer to Monsanto

After receiving his PhD, Craford had a number of job gives. Probably 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 threat. 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,” mentioned Craford, “however who knew?”

In his early days at Monsanto, Craford experimented with each lasers and LEDs. He targeted on LEDs full time when it grew to become 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] printed the work, he put the names of the blokes he had rising crystals and placing the issues collectively forward of his identify.”
—Nick Holonyak

The breakthrough that allowed Craford and his staff to transcend Holonyak’s pink 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 normally higher than oblique for LEDs, Craford defined, however the oblique kind nonetheless needs to be used due to band gaps large 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 printed 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 printed outcomes. “We determined that we may develop higher crystal and the experiment would work for us,” he mentioned.

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

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

—George Craford

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

His friends, nonetheless, have acknowledged Craford because the inventive drive behind yellow LEDs, and he was 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 mentioned, “was, ‘Wow, that’s nice, however our clients are very pleased with pink LEDs. Who wants different colours?’”

Westward ho!

After the LED work was printed, a Monsanto reorganization bumped Craford up from the lab bench to supervisor of superior know-how. One among his first duties was to pick researchers to be laid off. He recollects this as one of many hardest jobs of his life, however subsequently discovered that he preferred administration. “You may have extra selection; you could have extra issues that you’re semi-competent in, although you pay the value of turning into loads much less competent in anyone factor,” he instructed
IEEE Spectrum.

Quickly, in 1974, he was bumped up once more to know-how director, and moved from Monsanto’s company headquarters in St. Louis to its electronics division headquarters in Palo Alto, Calif. Craford was answerable for analysis teams creating know-how 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,” mentioned David Russell, Monsanto’s director of selling throughout Craford’s tenure as know-how director. “He’s a pure mental scientist to a fault for an outdated peddler like me.”

Although all the time the scientist, Craford additionally has a repute for relating nicely to individuals. “George is ready to categorical difficult technical points in a manner that each one of us can perceive,” mentioned James Leising, product improvement 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 capable of work out the conflicts and stroll away buddies. 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 government, Craford takes credit score for no particular person achievements at Monsanto throughout that point, however mentioned, “I used to be pleased with the truth that, one way or the other, we managed to be worldwide opponents in all our companies.” Even so, Monsanto determined to dump its optoelectronics enterprise and provided Craford a job again in St. Louis, the place he would have been accountable for analysis and improvement within the firm’s silicon enterprise.

Craford thought of this supply lengthy and exhausting. He preferred 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 may discover that may let him work with LEDs was a giant step down from know-how director—a place as R&D part supervisor, directing fewer than 20 individuals. This meant a lower 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 shortage of closed workplaces promotes collaboration. At HP, he interacts extra with engineers, and there’s a better sense that the entire group is pulling collectively. It’s extra open and communicative—it needs to be, with most engineers’ desks merely 1.5 meters aside. “I like the entire fashion 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 underneath him. (He nonetheless has the cubby and steel 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 foul factor for an R&D supervisor to say that each mission we’ve performed has been profitable, as a result of then you definitely’re not taking sufficient probabilities; nonetheless, we do must generate sufficient revenue for the group on what we promote to remain worthwhile.”

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

Craford walks that path between conservatism and threat in his private life as nicely, though some individuals won’t consider it, given his penchant for adventurous sports activities: skydiving, whitewater canoeing, marathon operating, and mountain climbing. These are measured dangers, based on Craford: ‘‘The Grand Teton is a severe 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 threat.”

Holonyak recollects an event when a bit of crystal formally confined to the Monsanto laboratory was handed to him by Craford on the grounds that an experiment Holonyak was trying was vital. Craford “may have gotten fired for that, however he was prepared to gamble.”

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

—George Craford

Craford is also called being an irrepressible asker of questions.

“His strategies of asking questions and issues brings individuals within the group to a better degree of pondering, reasoning, and problem-solving,’’ Kish mentioned.

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

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

The most recent era of LEDs, Craford mentioned, may substitute incandescent lights in lots of functions. One use is for exterior lighting on cars, the place the lengthy life and small dimension of LEDs allow automotive designers to mix decrease meeting prices with extra uncommon styling. Site visitors alerts 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.

From Your Site Articles

Related Articles Around the Web



Please enter your comment!
Please enter your name here

Most Popular

Recent Comments