Posted in | Semiconductor

New Microscopic Mechanism Allows Beryllium Atoms to be Used in Gallium Nitride

A breakthrough in reviewing methods largely discarded 15 years ago has been achieved by physicists at Aalto University.

Sample chamber of the positron accelerator. Photo: Hanna Koikkalainen

These physicists have discovered a microscopic mechanism capable of allowing gallium nitride semiconductors to be employed in electronic devices that distribute huge amounts of electric power.

The trick here is to be able to use beryllium atoms in gallium nitride. Gallium nitride is considered to be a compound extensively used in semiconductors in consumer electronics ranging from game consoles to LED lights. To be useful in devices that have to process more energy than in everyday home entertainment, however gallium nitride will have to be manipulated in different way on 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.

Professor Filip Tuomisto, Aalto University.

Experiments with beryllium doping were performed in the late 1990s in the hope that beryllium could be more efficient as a doping agent than the basic magnesium empoyed in LED lights. The work proved to be unsuccessful and research on beryllium was mainly discarded.

Working with scientists in Warsaw and Texas, researchers at Aalto University have recently succeeded to show – thanks to improvements in computer modeling and experimental techniques – that beryllium can in fact perform useful functions in gallium nitride. The article published in Physical Review Letters demonstrates that based on whether the material is cooled or heated, beryllium atoms will be able to switch positions, changing their nature of either accepting or donating electrons.

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.

Professor Filip Tuomisto, Aalto University.

Power electronics will be able to move to a totally new realm of energy efficiency if the beryllium-doped gallium nitride structures and their electronic properties can be completely controlled.

“The magnitude of the change in energy efficiency could as be 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 per cent by cutting the energy losses in power distribution systems,” says Tuomisto.

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