Diamonds De Novo

7 minute read
Alice Park

Peer through the small window of one of Apollo Diamond’s canister-like reactors, and it might seem as if you’re staring at something from out of this world. The inside of the cramped chamber is bathed in a magenta glow more befitting a Los Angeles nightclub than a science lab. Evenly arrayed on a small plate at the center of this colorful haze are what looks like 16 lozenges burning with an even deeper pink hue.

As unlikely as it seems, each of those small pinkish disks is a diamond, growing from a tiny seed crystal under conditions carefully created and monitored by Apollo’s proprietary software. Chemically, Apollo’s creations are no different from the diamond that is squeezed from carbon deep in the earth at incredible pressure and temperature. “It still blows people’s minds that you can manufacture diamond,” says Bryant Linares, president and CEO of the 17-year-old company based in suburban Boston. “People still feel that there is something mystical about diamonds and how they are made.”

But ever since the 1950s, when scientists created the first synthetic diamond bits (they were so tiny that they were more like diamond grit), researchers have been slowly demystifying the diamondmaking process and systematically trying to replicate it. Small bits of diamond–produced in a lab under extremely high pressure and temperature and used in cutting tools, optical equipment and lasers–are easy to generate. This type of production has become so routine that thousands of small plants all over China pour out synthetic diamonds suitable for cutting stone. Gem-quality diamonds of one carat or more, however, are trickier because at that size it’s difficult to consistently produce diamonds of high quality, even in the controlled environment of a lab. But after a half-century of trial and error, that may be changing. Several diamondmaking companies are starting to produce high-quality diamonds to rival the stones emerging from mines, and they could supply enough of them to open up new applications for the use of diamond that stretch far beyond pretty pieces of jewelry.

It turns out that as beautiful as a polished diamond is to look at, it also possesses physical and chemical properties that make it an ideal workhorse material for everything from semiconductors to biosensors. “To my mind, it’s a case of finding what diamond enables that nothing else can do,” says Donald Sadoway, a professor of materials science at Massachusetts Institute of Technology. Because it conducts heat so well, for example, diamond could be particularly useful for the small-electronics industry, which relies on ever more powerful processors that generate incredible amounts of heat. (Just try working with your laptop computer actually on your lap for a few hours.) “When you go to the next-generation semiconductor, you’re running something not too different from a toaster oven,” Sadoway says. Because it doesn’t retain heat, diamond can run processors of supercomputing power at lower temperatures compared with processors using silicon, the industry standard today. The molecular structure of diamond makes it ideal for handling high voltages like those found in switches for big municipal power grids. Physically, diamond’s toughness allows it to withstand the searing heat of more sophisticated lasers and even the brutal extremes of temperature and pressure faced by the windows on spacecraft as they leave and re-enter Earth’s atmosphere. And diamond’s ability to resist corrosion from acids and other organic compounds makes it a good material for biological sensors that may one day be implanted in the human body.

It’s this list of potential applications–and their untapped economic potential–that has attracted so much interest. The U.S. Navy and Army are investigating diamond’s usefulness both as a next-generation power-grid switch and as a wear-resistant coating for military equipment. Gemesis, a Sarasota, Fla., company that has been selling man-made gemstones for four years, sets aside a chunk of its R&D budget for the electronics industry. Even DeBeers, the dominant producer of mined gemstone diamonds, has acknowledged the la- tent power of synthetic diamonds (the preferred industry term). DeBeers has maintained a small business selling diamond for drills, precision cutting tools and even tweeter domes in stereo systems, but in 2002 it rebranded that branch of its operations Element Six–a sign of its commitment to this fledgling side of the business. “The market for industrial diamond is growing at 10% to 15% per annum,” says Element Six spokesman John Caldwell. “We are trying to push the boundaries of uses for diamond.”

Still, creating a diamond semiconductor is no easy feat. Rather than trying to mimic the conditions under which diamond is generated deep in the earth, Apollo, Element Six and most of the other leading diamondmakers are relying on a process called chemical vapor deposition (CVD). It’s a low-pressure, high-temperature method that uses heat energy from plasma and a combination of gases to rain carbon atoms on a starter seed of the gem, which gradually grows into a larger single-crystal diamond. CVD produces a more uniform, consistent diamond in sizes large enough to make an effective transistor. Using the diamond it created in its reactors as a “mother seed,” Apollo Diamond can now grow wafers that are large enough and of a quality that would make them useful in electronic devices. “You need to make mother seeds that will allow you to control the end product,” Linares says. “For semiconductor manufacturing, that means an extremely smooth and flat surface. For the first time, we’ve done that.” Over the next 12 months Apollo plans to build up a generation of mother wafers at least an inch in length that can consistently beget more high-quality diamond slivers, and then to enter the industrial market.

Apollo and its competitors are close to perfecting the manufacturing process, but it’s unlikely that man-made diamond will replace silicon entirely. Diamond manufacturing remains expensive, even after several spikes in silicon-wafer prices over the past year. But semiconductor researchers remain optimistic about diamond’s future role; at the very least, a combination of silicon and diamond could produce more powerful devices that run at cooler temperatures. Says Mike Mayberry, director of components research at Intel: “We’re still interested enough to keep an eye on it.”

Also tracking the progress of diamondmaking are biologists, who covet the gem’s inertness–it doesn’t react with other substances–and its ability to retain its structural integrity despite being bathed in natural acids and other organic compounds. One possible application: diamond-based electrodes, implanted under the skin, that could be designed to react chemically in the presence of certain proteins. Already, researchers at Case Western Reserve University have developed such a prototype for detecting levels of a protein critical to nerve-cell activity.

Since it may be another decade before such medical applications of diamond become a reality, for now Apollo is using the same CVD process to produce gem-quality stones for the retail market. Just last year the company started selling rough-cut gems to a Boston jewelry retailer. It may prove to be a smart strategy until the industrial market matures; thanks to booming economies in China and India, retail sales of diamond jewelry have been surging for a decade. Analysts expect up to 20% annual growth in the diamond market in China alone. With current mine capacities, that translates to a potential $10 billion worth of unmet demand by 2015–a gap that man-made diamonds could soon help fill. In support of the nascent field, last month the Gemological Institute of America, the leading grader of diamonds, agreed to rate synthetic diamonds on the same four Cs–carat, cut, color and clarity–used to evaluate natural diamonds. So even after the last stone is mined, perhaps one day diamonds really will be forever.

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