Improving the GaN-on-GaN Schottky Barrier Diode by ALD-AlN Tunneling Barrier Layer and Multi-Fins Structure

In this paper, we report a 1.84 kV GaN-on-GaN Schottky barrier diode (SBD) corresponds to a low on-resistance of 1.98 mΩ-cm2. The GaN epi-layer was etched to the multi-fins-structure with optimized bevel angle. The fins structure enables to improve the breakdown voltage by means of the uniforme electric field distribution. Afterwards, the GaN fins were capped by atomic layer deposition (ALD)-grown AlN film. The AlN served as a tunneling-barrier layer, which not only passivated the GaN surface but also decreased the turn-on voltage. The AlN-capped SBD shows a turn-on voltage at 0.18 V. Furthermore, the temperature-dependent transfer characteristics suggest the different current tunneling mechanisms at low and high electric field conditions, respectively. The time-dependent dielectric breakdown (TDDB) measurement suggests the surface traps were well passivated by ALD-AlN, which implies that the AlN cap-layer enables to improve the device reliability.