Fully- and Quasi-Vertical GaN-on-Si p-i-n Diodes: High Performance and Comprehensive Comparison

We report growth and fabrication of fully- and quasi-vertical GaN-on-Si p-i-n diodes. A record high Baliga figure of merit of 304 and 152 MW/cm2is reported for fully-and quasi-vertical GaN-on-Si p-i-n diodes, respectively. A comprehensive comparison has been made between the two kinds of diodes in regard ON-resistance, breakdown voltage, and switching performance. An ultralow differential ON-resistance of 0.5 and 1.0 mQ · cm2has been demonstrated for quasi- and fully-vertical diodes with a diameter of 60 μm at 3 kA/cm2. Current crowding effect in the n-GaN was a dominant factor of RON, especially for large size quasi-vertical diodes at high current density. A high Vbrof 390 V has been demonstrated for the two types of device structures, regardless of device diameters. The same breakdown voltage and low off-state leakage indicated the reliability of fully-vertical device fabrication that reflects intrinsic properties of the grown epilayers. The two kinds of diodes share similar switching performance, which is much superior to a commercial fast-recovery Si diode as a reference. The device characteristics show promising potential of both fully-and quasi-vertical diodes for low-cost high-power applications.