Recorded 1.4 kV/1.24 GW/cm2 BFOM AlGaN/GaN Schottky barrier diodes grown on Si substrate with fan-shaped AlGaN polarization superjunction

Abstract

In this work, AlGaN/GaN Schottky barrier diodes on silicon (Si) substrates are proposed and fabricated. The proposed devices feature fan-shaped AlGaN polarization field plates (FPs) with a gradient decrease in Al content along the [0001] direction. The resulting negative polarization-induced bulk charges effectively extend the depletion region in the GaN drift layer and homogenize the electric field distribution near both the Schottky contact region and the FP edge. Benefiting from the strong polarization charge-coupling effect enabled by the fan-shaped structures, the electric field can be efficiently modulated while preserving efficient two-dimensional electron gas conduction under forward bias. As a result, the proposed devices achieve a low specific on-resistance (Ron,sp) of ∼1.58 mΩ cm2 together with a high breakdown voltage of ∼1400 V, yielding a recorded Baliga figure of merit of ∼1.24 GW/cm2. Electrical-stress measurements further show a pronounced reduction in dynamic Ron,sp degradation. This confirms that the electron trapping effect is effectively suppressed. These results demonstrate that polarization charge engineering that is combined with fan-shaped FP structures favors a three-dimensional charge-coupling effect. As a result, a highly effective strategy for simultaneously improving static performance and dynamic stability in Si-based GaN power devices has been provided.