Electric field modulation technique for high-voltage AlGaN/GaN Schottky barrier diodes

A novel structure of AlGaN/GaN Schottky barrier diode (SBD) featuring electric field optimization techniques of anode-connected-field-plate (AFP) and magnesium-doped p-type buried layer under the two-dimensional electron gas (2DEG) channel is proposed. In comparison with conventional AlGaN/GaN SBDs, the magnesium-doped p-type buried layer in the proposed structure can provide holes that can help to deplete the surface 2DEG. As a result, surface field strength around the electrode edges is significantly suppressed and the electric field along the channel is distributed more evenly. Through 2D numerical analysis, the AFP parameters (field plate length, L_AFP, and field plate height, T_AFP) and p-type buried layer parameters (p-type layer concentration, N_P, and p-type layer thickness, T_P) are optimized to achieve a three-equal-peak surface channel field distribution under exact charge balance conditions. A novel structure with a total drift region length of 10.5 μm and a magnesium-doped p-type concentration of 1×10¹⁷ cm^-3 achieves a high breakdown voltage (V_B) of 1.8 kV, showing 5 times improvement compared with the conventional SBD with the same device dimension.