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-2under direct-current operation offering a specific on-state resistanceRon-Aof 2.2 mΩ·cm2. With 80 μs pulses applied to the gate, the devices showed no dispersion. The increased aperture lengthLapresulted in the decrease in specificRon, as expected. The impact of the gate overlap to apertureLgoon the leakage current was studied, where the leakage current was found to increase with a smaller overlap.