Gallium nitride boosted into high-power realm
R Colin Johnson
2/2/2011 2:51 PM EST
PORTLAND, Ore.—Gallium nitride is lauded as the next-generation material for high-power electronics, but until now has been plagued by breakdown above about 250 volts, according to researchers at North Carolina State University. The researchers claim to have discovered a technique to raise breakdown to 1,650 volts, thereby boosting power handling by 10 times.
These high-power handling GaN devices will be useful for emerging applications ranging from smart-grid to electric cars.
By implanting a neutral species—argon—alongside its termination electrode (see figure) the electrical fields are spread out, thereby preventing premature breakdown, according to professor Jay Baliga, who performed the work with doctoral candidate Merve Ozbek.
By flanking a galliun nitride (GaN) device termination with ion implantation (green) researchers boosted GaN breakdown voltage from 300 to 1,650 volts.
"One of the major problems of high voltage power devices is pre-mature breakdown at its edges. Our work demonstrates a novel planar edge termination technique for GaN devices with which nearly ideal plane parallel breakdown voltages can be achieved by creating a thin amorphous layer at the edge of the device by using argon ion-implantation," said Ozbek. "The implantation creates a thin high resistivity region at the surface beyond the edges of the diode which promotes the spreading of the potential along the surface reducing the electric field."
The researchers tested their technique by fabricating Schottky diodes, raising their breakdown voltage by almost seven times to 1,650 volts. As a result, the electrical resistance of the devices was reduced by 100-times, thereby allowing the 10-fold boost in power handling capabilities.