Comprehensive Design and Numerical Study of GaN Vertical MPS Diodes Towards Alleviated Electric Field Crowding and Efficient Carrier Injection

Abstract

In recent years, gallium nitride (GaN) has exhibited tremendous potential for power electronic devices owing to its wider energy band gap, higher breakdown electric field, and higher carrier mobility [1]–[4]. Thanks to the availability of low-dislocation-density bulk GaN substrates and the intrinsic advantages of the vertical device topology, GaN-based vertical SBDs have been developed extensively towards high voltage and high current applications [5]–[7]. However, similar to the lateral GaN SBDs based on the AlGaN/GaN heterostructures, GaN vertical SBDs also suffer from reverse leakage issues due to the energy barrier lowering effect at high reverse bias condition. To achieve a decent device performance, several device architectures have been developed, such as junction barrier Schottky (JBS) diode [8], MPS diode [9]–[12], and trench metal-insulator-semiconductor barrier Schottky (TMBS) diode [13], [14], which are designed to move the peak electric field from the interface of the Schottky junction to the inside of the device at high reverse bias, leading to a higher breakdown voltage and a lower reverse leakage current.

Keywords

• Breakdown voltage
• device optimization
• gallium nitride (GaN)
• specific ON-resistance
• vertical merged pn-Schottky (MPS) diode