Integrated 100 V bootstrap diode with enhanced reverse recovery characteristics for eGaN-field effect transistor gate drivers

An integrated 100 V bootstrap diode (D-BST) with anode engineering based on the double epitaxial process for enhancement mode gallium nitride (eGaN) transistor gate drivers is first proposed in this Letter. On the anode side, the P + dynamic field limiting ring (PDFLR) and the floating metal electrode (FME) are employed. The PDFLR can greatly suppress the peak electric field on both sides of the device during the reverse recovery period, which leads to a significant improvement in reverse recovery robustness. The FME lowers the anode injection efficiency in on-state and increases the hole recombination rate during reverse recovery, therefore, a fast reverse recovery is realised. The partial heavy doped N-type buried layer not only reduces the resistance of the drift region but also shortens the hole extraction path from the drift region to sub-electrode, as a result, reverse recovery tail current can be greatly shortened. Experiments combined with simulations show that the reverse recovery robustness of the optimised proposed D-BST is improved by more than 12 times. Furthermore, the reverse recovery charge (Q(rr)) of the proposed structure is only 3.2 nC, which is 22% lower than that of the conventional device at the same forward current (I-F) of 0.1 A.