Modifying methods largely abandoned 15 years ago, physicists have made a breakthrough. They have discovered a microscopic mechanism that will allow gallium nitride semiconductors to be used in electronic devices that distribute large amounts of electric power.
The key is using beryllium atoms in gallium nitride. From LED lights to game consoles, gallium nitride is a compound that has many applications as a semiconductor in consumer electronics. Its effectiveness in devices that handle significantly more energy than common home entertainment gadgets, though, depends on manipulating gallium nitride in new ways at the atomic level.
"There is growing demand for semiconducting gallium nitride in the power electronics industry. To make electronic devices that can process the amounts of power required in, say, electric cars, we need structures based on large-area semi-insulating semiconductors with properties that allow minimizing power loss and can dissipate heat efficiently. To achieve this, adding beryllium into gallium nitride — or 'doping' it — shows great promise," explains Professor Filip Tuomisto from Aalto University.
In the late 1990s, scientists conducted experiments with beryllium doping in the hope that beryllium would prove more efficient as a doping agent than the prevailing magnesium used in LED lights. The work proved unsuccessful, however, and research on beryllium was largely set aside.
Now, advances in computer modeling and experimental techniques such as positron annihilation spectroscopy have allowed researchers to demonstrate that beryllium can, in fact, perform useful functions in gallium nitride.
In collaboration with scientists from Texas State University and the Polish Academy of Sciences, investigators at Aalto University published an article in Physical Review Letters demonstrating that beryllium atoms will change positions, altering their nature of either donating or accepting electrons depending on whether the material is heated or cooled.
"Our results provide valuable knowledge for experimental scientists about the fundamentals of how beryllium changes its behavior during the manufacturing process. During it — while being subjected to high temperatures — the doped compound functions very differently than the end result," describes Tuomisto.
The energy efficiency of power electronics could be improved significantly if the beryllium-doped gallium nitride structures and their electronic properties can be fully controlled.
"The magnitude of the change in energy efficiency could be as similar as when we moved to LED lights from traditional incandescent light bulbs. It could be possible to cut down the global power consumption by up to ten percent by cutting the energy losses in power distribution systems," says Tuomisto.