Argon buffer helps GaN devices handle higher voltages

Researchers in the US believe they have solved the problem of gallium nitride (GaN) failing when exposed to a high voltage.

GaN is said to be a promising material for use in emerging high-power devices that are more energy efficient than existing technologies

However, the material’s sensitivity to high voltages has proved a stumbling block.

Researchers at North Carolina State University have solved the problem, introducing a buffer made of argon that allows the GaN devices to handle 10 times greater power.

‘For future renewable technologies, such as the smart grid or electric cars, we need high-power semiconductor devices and power-handling capacity is important for the development of those devices,’ said Merve Ozbek, a PhD student at NC State and author of a paper describing the research.

Previous research into developing high-power GaN devices is said to have run into obstacles, because large electric fields were created at specific points on the devices’ edge when high voltages were applied — effectively destroying the devices.

NC State researchers have addressed the problem by implanting the buffer at the edges of GaN devices. The buffer spreads out the electric field, allowing the device to handle much higher voltages.

The researchers tested the technique on Schottky diodes and found that the argon implant allowed the GaN diodes to handle almost seven times higher voltages.

The diodes that did not have the argon implant broke down when exposed to approximately 250V. The diodes with the argon implant could handle up to 1,650V before breaking down.

‘By improving the breakdown voltage from 250 to 1,650V, we can reduce the electrical resistance of these devices one-hundredfold,’ said Dr Jay Baliga, professor of electrical and computer engineering at NC State, and co-author of the paper. ‘That reduction in resistance means that these devices can handle 10 times as much power.’

The paper, ‘Planar, nearly ideal edge-termination technique for GaN devices’, is forthcoming from IEEE’s Electron Device Letters.