2.2 kV Breakdown Voltage AlGaN/GaN Schottky Barrier Diode with Polarization Doping Modulated 3D Hole Gas Cap Layer and Polarization Junction Structure

We report a AlGaN/GaN Schottky barrier diode (SBD) with polarization doping modulated three-dimensional hole gas (3DHG) cap layer (PDHG cap layer) and polarization junction (PJ) and systematically investigate the impact of the length of the PDHG layer on reverse and forward characteristics by numerical simulation. In an SBD with polarization junction structure (PJ-SBD), the positive and negative polarization charges at PJ heterointerfaces are compensated at reverse voltage and the electric field and carrier depletion region are redistributed, which alleviate the electric field crowding effect at the edge of Schottky anode. In an SBD with PDHG and PJ structures (PDHG-PJ-SBD), the PDHG layer can further get a higher average electric field and forms a PDHG/GaN p-n diode connected to a Schottky anode in parallel, which improves the reverse blocking capability and reduces R on,sp , when compared with a PJ-SBD. The result shows that the PDHG-PJ-SBD has the most superior reverse performance when compared to the PJ-SBD and conventional SBD. In the PDHG-PJ-SBD, a higher breakdown voltage (V BD ) and lower leakage current has been achieved. We find that the length of the PDHG is closely associated with electric field distribution and reverse characteristics of the PDHG-PJ-SBD. The best performance is found in the PDHG-PJ-SBD when the length of the PDHG cap layer is 4 μm, with a high breakdown voltage of 2258 V, a specific on-resistance (R on,sp ) of 2.7 5mΩ cm 2 , a turn-on voltage of 0.64 V and Baliga’s figure of merit (BFOM) of 1854 MW/cm 2 , which is almost 84 times higher compared to a conventional SBD with BFOM = 21 MW/cm 2 .