CAVET on Bulk GaN Substrates Achieved With MBE-Regrown AlGaN/GaN Layers to Suppress Dispersion

A current aperture vertical electron transistor (CAVET) with a Mg-ion-implanted current blocking layer (CBL) and a channel regrown by plasma assisted molecular beam epitaxy (MBE), is successfully demonstrated on bulk GaN to work as a high voltage device. The fabrication of the device combined a drift region grown by metalorganic chemical vapor deposition (MOCVD), to hold the blocking voltage, with AlGaN/GaN layers regrown by plasma-MBE to conduct current. The device registered a maximum current of 4 kA· cm<sup>-2</sup> under direct-current operation offering a specific on-state resistance <i>R</i><sub>on</sub> - <i>A</i> of 2.2 mΩ·cm<sup>2</sup>. With 80 μs pulses applied to the gate, the devices showed no dispersion. The increased aperture length <i>L</i><sub>ap</sub> resulted in the decrease in specific <i>R</i><sub>on</sub>, as expected. The impact of the gate overlap to aperture <i>L</i><sub>go</sub> on the leakage current was studied, where the leakage current was found to increase with a smaller overlap.

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