Vertical GaN-on-Tungsten High Voltage pn-Diodes

In this study, we present vertical GaN based pn-diodes designed for high-voltage applications. These devices were initially grown and processed on 4-inch sapphire substrates and subsequently transferred to 4-inch tungsten substrates, enabling a fully vertical conduction path. Laser lift-off was employed to detach the GaN-membrane device structures from their original sapphire substrate. The diodes exhibit enhanced forward conduction following the transfer process, with the ON-state resistance decreasing from 1.52 ± 0.05 mΩcm2 to 1.15 ± 0.05 mΩcm2. During this time, the blocking strength remains largely unaffected, with its wafer level median value decreasing marginally from 1015 ± 47 V to 988 ± 57 V. The high device yields achieved through the membrane transfer procedure highlight the cost-competitiveness of this vertical GaN device technology for high-power applications, eliminating the need for expensive GaN substrates.