Vertical Geometry, 2-A Forward Current Ga2O3 Schottky Rectifiers on Bulk Ga2O3 Substrates

Large area (up to 0.2 cm²) Ga₂O₃ rectifiers without edge termination were fabricated on a Si-doped n-Ga₂O₃ drift layer grown by halide vapor phase epitaxy on a Sn-doped n⁺Ga₂O₃ (001) substrate. A forward current of 2.2 A was achieved in single-sweep voltage mode, a record for Ga₂O₃ rectifiers. The on-state resistance was <inline-formula> <tex-math notation="LaTeX">$0.26~\Omega ~ \cdot$ </tex-math></inline-formula> cm² for these largest diodes, decreasing to <inline-formula> <tex-math notation="LaTeX">$5.9\times 10^{-4} \Omega \,\, \cdot$ </tex-math></inline-formula> cm² for <inline-formula> <tex-math notation="LaTeX">$40\times 40\,\,\mu \text{m}^{2}$ </tex-math></inline-formula> devices. The temperature dependence (25 °C–125 °C) of forward current density was used to extract the barrier height of 1.08 eV for Ni and a Richardson’s constant of 48 A <inline-formula> <tex-math notation="LaTeX">$\cdot$ </tex-math></inline-formula> cm⁻² <inline-formula> <tex-math notation="LaTeX">$\cdot \,\,\text{K}^{-2}$ </tex-math></inline-formula>. Ideality factors were in the range 1.01–1.05, with the barrier height decreasing with temperature. The reverse breakdown was a strong function of diode area, decreasing from 466 V (<inline-formula> <tex-math notation="LaTeX">$1.6\times 10^{-5}$ </tex-math></inline-formula> cm² to 15 V for 0.2 cm². This led to power figure-of-merits (<inline-formula> <tex-math notation="LaTeX">${V}_{B}^{2}/\text{R}_{\mathrm{ON}})$ </tex-math></inline-formula> in the range <inline-formula> <tex-math notation="LaTeX">$3.68\times 10^{8}$ </tex-math></inline-formula>–865 W <inline-formula> <tex-math notation="LaTeX">$\cdot$ </tex-math></inline-formula> cm⁻² over this area range. The reverse breakdown voltage scaled approximately as the contact perimeter, indicating it was dominated by the surface and decreased with temperature with a negative temperature coefficient of 0.45 V <inline-formula> <tex-math notation="LaTeX">$\cdot \,\,\text{K}^{-1}$ </tex-math></inline-formula>. The reverse recovery time when switching from +1 V to reverse bias was 34 ns.