Reduction Of On-Resistance And Current Crowding In Quasi-Vertical Gan Power Diodes

This paper studies the key parameters affecting on-resistance and current crowding in quasi-vertical GaN power devices by experiment and simulation. The current distribution in the drift region, n(-)-GaN, was found to be mainly determined by the sheet resistance of the current spreading layer, n(+)-GaN. The actual on-resistance of the drift region significantly depends on this current distribution rather than the intrinsic resistivity of the drift layer. As a result, the total specific on-resistance of quasi-vertical diodes shows a strong correlation with the device area and sheet resistance of the current spreading layer. By reducing the sheet resistance of the current spreading layer, the specific on-resistance of quasi-vertical GaN-on-Si power diodes has been reduced from similar to 10 m Omega.cm(2) to below 1 m Omega.cm(2). Design space of the specific on-resistance at different breakdown voltage levels has also been revealed in optimized quasi-vertical GaN power diodes. Published by AIP Publishing.