Panasonic recently announced that researchers developed a new technique to drastically increase the blocking voltage of Gallium Nitride based power switching transistor on silicon substrates. The blocking voltage of the Si substrate can be added to that of the GaN transistor by the new structure which will enable the blocking voltage over 3000V. Panasonic investigates the mechanism and reveals that the increase is limited by leakage current at the interface between GaN and Si caused by electrons formed as an inversion layer. As a technical solution for it, Panasonic proposes a new technology called Blocking-Voltage-Boosting (BVB) structure which consists of selectively formed p-type regions on the surface of the Si substrates. The p-type regions prevent the inversion electrons from flowing as leakage current. The fabricated GaN transistor on Si with the BVB structure achieves high breakdown voltage of 2200V with the total epitaxial thickness as small as 1.9 m. This value is approximately five times higher than that in the conventional GaN transistor on Si with the same thickness of GaN. Further increase of the epitaxial thickness will enable the break down voltages over 3000V with existing epitaxial technologies. The GaN transistor on Si with the BVB structure will be applicable to various switching systems with higher operating voltages.
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