Optimizing the Preparation Process of Quasi-Vertical GaN p-i-n Diode to Reduce Reverse Leakage and Increase Switching Ratio

In order to reduce the reverse leakage current of gallium nitride (GaN) p-i-n diode and improve the switching ratio of the device, the preparation process of GaN based quasi-vertical p-i-n diode was optimized from three aspects. First, the effects of metal and oxide etching masks on GaN step etching were compared, and it was found that the device etched with metal nickel (Ni) mask had better positive characteristics than silicon dioxide (SiO2) mask. Secondly, sidewall treatment was used to repair the damaged sidewall after etching, and the repair mechanism was discussed. Finally, the passivation layer was prepared by low temperature and high temperature growth respectively, and the performance of the device under different process conditions was compared. After the optimization of the preparation process, the leakage current of the quasi-vertical p-i-n diode was reduced by three orders of magnitude compared with the control group. The optimized device exhibits an ideal factor n of 1.12, turn-on voltage (Von) of 3.34 V, specific on-resistance (Ron,sp) of 2.27 m $\Omega \cdot $ cm2, positive and negative current density of 161.54 A/cm2 and $2.55\times 10^{-9}$ A/cm2, respectively, and a switching ratio of $6.35\times 10^{10}$ .