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^-2 under direct-current operation offering a specific on-state resistance R_on - A of 2.2 mΩ·cm². With 80 μs pulses applied to the gate, the devices showed no dispersion. The increased aperture length L_ap resulted in the decrease in specific R_on, as expected. The impact of the gate overlap to aperture L_go on the leakage current was studied, where the leakage current was found to increase with a smaller overlap.