High Performance β-Ga2O3 vertical Schottky Barrier Diodes

Gallium oxide (Ga ₂ O ₃ ) has received much attention in recent years, for its ultra-wide bandgap (4.5-4.8 eV), high theoretical breakdown field (8 MV/cm), low cost and large-size native substrate. Benefiting from the high current handling capability, Ga ₂ O ₃ vertical Schottky barrier diodes (SBDs) are much more desirable for power switching applications. However, there is a high-density interface state at the dielectric/Ga ₂ O ₃ interface in the vertical β-Ga ₂ O ₃ SBDs, resulting in high reverse leakage current and poor breakdown characteristics. To overcome the aforementioned problem, a high-performance vertical β-Ga ₂ O ₃ Schottky Barrier Diode (SBD) with a novel homologous air bridge field plate (HABFP) is reported. An air space is constructed at the foot of the anode, using a double dielectric layer with 20 nm SiO ₂ and 300 nm SiN _x by self-aligned wet etching. The HABFP structure effectively suppresses the high peak electric field at anode foot, since the anode metal is separated from the dielectric/Ga ₂ O ₃ interface. Compared with devices with a conventional field plate (CFP) using single SiN _x or SiO ₂ , the fabricated HABFP β-Ga ₂ O ₃ SBD demonstrates a much higher breakdown voltage (V _br ) of 1100 V, while maintaining a relatively low specific on-resistance (Ron,sp) of 1.83 mΩ·cm ² . Besides, the mechanism of the novel HABFP structure on the performance of β-Ga ₂ O ₃ SBD is also analyzed, indicating that HABFP structure is a simple and effective termination technique.