Curvature-Adaption Termination with for Wide-Bandgap Semiconductors Vertical Power Devices

The curvature effect poses a significant challenge to the field termination structure, particularly in wide-bandgap (WBG) semiconductors used in power electronics. This work proposes a curvature-adaption termination (CAT) that effectively mitigates the curvature effect, achieving a more uniform electric field distribution and maximizing the voltage endurance capability of wide-bandgap semiconductors. The field termination structure is segmented into two sections based on depletion depth: the completely depleted region (CDR) and the partially depleted region (PDR). The CAT structure, developed through a two-step method, aims to strike a harmonious balance between CDR and PDR designs. By widening the rings in the CDR region and adjusting the curvature of the depleted line in the PDR region, the CAT structure successfully alleviates electric field concentration without necessitating an increase in termination area. This innovative design ensures a more uniform electric field distribution and optimizes the voltage endurance capacity of GaN devices. When applied to GaN vertical devices, the proposed CAT structure enables the blocking voltage (BV) to reach 93% (1950 V) of the critical value of the ideal device cell while maintaining on-resistance (Ron) and avoiding additional process steps. Furthermore, the CAT structural design can be extended to other vertical GaN power devices, such as JBS and p-n diodes. With the incorporation of the CAT structure, the BV of the vertical GaN JBS and p-n diode reaches 93% (1950 V) and 92% (1930 V) of the critical value of the ideal device cell, respectively. These outstanding properties demonstrate that the proposed CAT structure has the potential to significantly improve WBG power electronics and serves as a promising candidate for further advancements in the field.