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

• Published in: IEEE transactions on electron devices Vol. 65; no. 7; pp. 2790 - 2796
• Main Authors: Yang, Jiancheng, Ren, Fan, Pearton, Steve J., Kuramata, Akito
• Format: Journal Article
• Language: English
• Published: IEEE 01.07.2018
• Subjects: Current measurement; Electric breakdown; Epitaxial growth; Forward current; Gallium; gallium oxide; Geometry; rectifiers; Schottky diode; Schottky diodes; Substrates
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2018.2838439

Large area (up to 0.2 cm 2 ) Ga 2 O 3 rectifiers without edge termination were fabricated on a Si-doped n-Ga 2 O 3 drift layer grown by halide vapor phase epitaxy on a Sn-doped n + Ga 2 O 3 (001) substrate. A forward current of 2.2 A was achieved in single-sweep voltage mode, a record for Ga 2 O 3 rectifiers. The on-state resistance was <inline-formula> <tex-math notation="LaTeX">0.26~\Omega ~ \cdot </tex-math></inline-formula> cm 2 for these largest diodes, decreasing to <inline-formula> <tex-math notation="LaTeX">5.9\times 10^{-4} \Omega \,\, \cdot </tex-math></inline-formula> cm 2 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> cm 2 to 15 V for 0.2 cm 2 . 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.