High-Breakdown-Voltage and Low-Specific-on-Resistance GaN p--n Junction Diodes on Free-Standing GaN Substrates Fabricated Through Low-Damage Field-Plate Process

In this letter, we describe the characteristics of Gallium Nitride (GaN) p--n junction diodes fabricated on free-standing GaN substrates with low specific on-resistance $R_{\text{on}}$ and high breakdown voltage $V_{\text{B}}$. The breakdown voltage of the diodes with the field-plate (FP) structure was over 3 kV, and the leakage current was low, i.e., in the range of $10^{-4}$ A/cm 2 . The specific on-resistance of the diodes of 60 μm diameter with the FP structure was 0.9 m$\Omega$$\cdot$cm 2 . Baliga's figure of merit ($V_{\text{B}}{}^{2}/R_{\text{on}}$) of 10 GW/cm 2 is obtained. Although a certain number of dislocations were included in the device, these excellent results indicated a definite availability of this material system for power-device applications.