Experimental study of edge termination in (001) β-Ga2O3 Schottky barrier diodes supported by anisotropic breakdown simulation

This paper presents a comprehensive theoretical and experimental investigation into the breakdown voltage (BV) limits of vertical β-Ga2O3 Schottky barrier diodes (SBDs) on (001) substrates. First, MATLAB and TCAD simulations incorporating anisotropic impact ionization coefficients were utilized to establish theoretical critical electric fields for different crystallographic orientations. To mitigate orientation-dependent field crowding, SBDs utilizing single zone (SZ) and multiple floating zone (MFZ) junction termination extensions (JTEs) were fabricated with varying nitrogen doses, demonstrating significant BV improvements over standard P+ Terminated devices. A systematic postdeposition rapid thermal annealing study was subsequently conducted to address metal-semiconductor contact issues, revealing an optimal thermal window that maximized the experimental BV. However, despite these edge termination and thermal optimizations, the maximum achieved BV remained at ∼900 V, well below the ideal theoretical limit of ∼(2–2.5) kV. This deviation is primarily attributed to a low nitrogen dopant activation rate of approximately 10%. To overcome this fundamental fabrication limitation, a novel Ring-Assisted (RA) JTE structure is proposed and simulated. The RA-JTE demonstrates high field-smoothing efficacy even at low implantation doses, providing a robust architectural solution to capture the low nitrogen activation reality in next-generation β-Ga2O3 power electronics.