By implanting a neutral species—argon—alongside its termination electrode (see figure) the electrical fields are spread out, thereby preventing premature breakdown,
"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.
The paper, "Planar, Nearly Ideal Edge Termination Technique for GaN Devices," is forthcoming from IEEE's Electron Device Letters.
Abstract: In this paper, a simple edge termination is described which can be used to achieve nearly ideal parallel plane breakdown voltage for GaN devices. This technique involves implanting a neutral species on the edges of devices to form a high resistive amorphous layer. With this termination, formed by using argon implantation, the breakdown voltage of GaN Schottky barrier diodes were increased from 300V for unterminated diodes to 1650V after termination.
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