From Smoots to Semiconductors
As a young boy, Jerry Woodall ‘60 took things apart to see how they worked, earning him the nickname “Tinker.” When he dismantled the family’s electric iron, his father sat Jerry down and told him not to take things apart unless he could put them back together. So Woodall focused on building, challenging himself to use every piece of his Lincoln Log set every time he created a new structure. And years later, when he was, as he puts it, “playing in the sandbox” in a lab at IBM, his passion for tinkering paid off: Woodall became one of the first people to produce new semiconductor materials and devices that would revolutionize the electronics industry.
Woodall grew up in a close-knit family in Takoma Park, MD. Undeterred by the fact that he was with born with only one useful eye, he pitched well in Little League, played Ping-Pong and tennis aggressively, and excelled in science in high school. A compelling pamphlet on nuclear fission fascinated him; envisioning himself as a nuclear physicist, he applied to MIT.
Woodall had never visited the Institute before he rode the overnight train from Washington, DC, to Back Bay Station and took a cab to Baker House in the fall of 1956. After a mediocre scholastic performance his freshman year, he struggled as a sophomore, flunking electricity and magnetism. (He would graduate with a C average.) But when he decided to major in metallurgy, he flourished under the guidance of his undergraduate thesis advisor, Professor Morris Cohen, a pioneer in materials science.
His social life improved when he joined the MIT choral society, became a backup pianist for the glee club, and was elected pledge master at his fraternity, Lambda Chi Alpha, where he’d helped carry out the famous Smoot-measuring exercise the year before. Woodall says that the idea sprang from an after-dinner discussion about the arbitrariness of units. To demonstrate this concept to the pledges, the assembled brothers came up with the idea of using Oliver Smoot, the shortest Lambda Chi pledge of the Class of 1962 at five feet seven inches tall, to measure the Harvard Bridge. Its length still stands at 364.4 Smoots plus or minus an ear.
After graduating in 1960, Woodall worked briefly as a staff engineer at Clevite Transistor Products. Two years later, he landed a job as a junior staff member at IBM’s new Watson Research Center in Yorktown Heights, NY. Morris Cohen recommended him strongly, urging an IBM personnel officer to ignore Woodall’s MIT grades because he had “a green thumb in a laboratory.”
Over the next five decades, Woodall coauthored 85 patents (mostly for IBM), published 365 articles in scientific journals, earned 30 consecutive annual IBM Invention Achievement Awards, and won an $80,000 prize from IBM for demonstrating the first working heterojunction, an interface between two semiconductor materials that would prove crucial in lasers, light-emitting diodes, and other devices. In 1982, while still at IBM, he earned a PhD in electrical engineering from Cornell University. He became an IBM fellow, the highest honor an IBM researcher can achieve, in 1985.
When Woodall joined the research team at the Watson Center in 1962, he was part of an IBM initiative to replace mechanical data-processing equipment with smaller, more powerful electronic devices. Encouraged to pursue open-ended research, he and IBM colleague Hans Rupprecht began looking for materials that could convert electricity to light at room temperature without using a lot of power. Their success led to practical uses for laser beams, which had previously been produced only at very low temperatures in processes that used a great deal of power.
But Woodall says his first big break in the lab came when he, Rupprecht, and others found a new way to make a light-emitting diode. LED technology was then in its infancy; the first devices, which emitted infrared light, used too much power to be practical. Woodall perfected a process known as liquid-phase epitaxy to grow exceptionally pure crystals of gallium arsenide, the semiconductor from which infrared LEDs are made. His success made it possible for his team to fabricate an infrared LED that was efficient enough for widespread applications. Today, such LEDs are ubiquitous in TV remote controls.
“I never invented anything brand-new. My work is engineering new workable and efficient materials and devices,” says Woodall. “My middle name is ‘Mr. Fix-It.’ ”
Woodall and Rupprecht next began working on a way to produce an LED that would emit visible light. But to do that, they needed a better semiconductor. In 1957, Herbert Kroemer, then a researcher at RCA, had proposed layering different types of semiconductors, predicting that the interfaces between them would let researchers control the flow of current through the material so that they could tailor its electronic properties to specific purposes. Although that insight would earn Kroemer the Nobel Prize in 2000, it took Woodall’s exceptional crystal-growing skills to help bring the idea to life. In 1967, Woodall and his colleagues used liquid-phase epitaxy to grow another alloy, gallium aluminum arsenide, on a gallium arsenide substrate. The compound semiconductor based on the so-called lattice-matched GaAlAs/GaAs heterojunction could be used to produce diodes that emitted extremely bright red light. The material was incorporated into a flood of new electronic applications, including CD players and fiber-optic communication devices.
By 1972, the space race was well under way, and the pressure was on to develop efficient solar cells to generate electricity for orbiting spacecraft and satellites. Woodall realized that a compound semiconductor that turned electricity to light could also turn light to electricity. He and Harold Hovel used their new heterojunction to develop a high-efficiency solar cell that could withstand the rigors of space. Woodall and colleagues would also employ the material in a transistor that is widely used today in satellite communication systems and cell phones.
The impact of Woodall’s heterojunction research would be staggering. By 2001, when President George W. Bush awarded him the National Medal of Technology, it was estimated that about half the annual $5 billion in sales of gallium arsenide-based semiconductor devices could be traced to his seminal publications and patents. For that work, Woodall has earned numerous awards besides the presidential medal, including the 2005 IEEE Jun-ichi Nishizawa Medal, the 2000 IEEE Third Millennium Award, and the 1997-1998 Eta Kappa Nu Vladimir Karapetoff Eminent Member’s Award. In 1989 he was elected to the National Academy of Engineering.
Now a professor of electrical and computer engineering at Purdue University, Woodall is working on developing a novel way of generating hydrogen in hopes of making it a more practical fuel. His current research focuses on an aluminum-rich alloy containing gallium, indium, and tin that can react with water to produce hydrogen and aluminum hydroxide. The aluminum hydroxide resulting from this reaction can be recycled back into aluminum through commercial electrolysis.
Woodall is focusing on two practical applications for this process. First, he hopes to add hydrogen to diesel engines to increase their combustion efficiency. He also thinks that ships could generate their own fuel by splitting seawater to release hydrogen.
Harnessing the planet’s abundant supply of hydrogen requires overcoming several challenges. For instance, the process of recycling aluminum hydroxide back into aluminum emits carbon, because it relies on carbon electrodes. But Woodall points out that a greener type of electrode is being developed, and he remains convinced that hydrogen power has a bright future. For Mr. Fix-It, daunting challenges are part of the fun.
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