| AVS 64th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Thursday Sessions |
| Session EM-ThP |
| Session: | Electronic Materials and Photonics Poster Session |
| Presenter: | Jiancheng Yang, University of Florida |
| Authors: | J.C. Yang, University of Florida S.H. Ahn, University of Florida F. Ren, University of Florida S.J. Pearton, University of Florida |
| Correspondent: | Click to Email |
A reverse breakdown voltage of 1600 V was demonstrated for Schottky diodes without edge termination fabricated on 10 µm epitaxial β-Ga2O3 grown bulk conductive substrate. Ga2O3 has a theoretical Baliga figure of merit (defined as VB2/RON, where VB is the reverse breakdown voltage and RON is the on-state resistance) significantly higher than more familiar wide bandgap semiconductors, due mainly to its larger bandgap (~4.5-4.8 eV) compared to that of 4H or 6H-SiC and GaN (~3.0-3.4 eV). The theoretical breakdown electric field is ∼8 MV/cm, with experimental demonstrations as high as 3.8 MV/cm and this is already higher than the bulk critical field strengths of both GaN and SiC. In this work, the β-Ga2O3 Schottky barrier diodes were fabricated in a vertical geometry structure consisting of Ni/Au rectifying contacts without edge termination on Si-doped epitaxial layers (10 µm, n~ 4×1015 cm-3) grown on Sn-doped bulk Ga2O3 substrates with full area Ti/Au back Ohmic contacts. The reverse breakdown voltage, VBR, was a function of rectifying contact area, ranging from 1600V at 3.1×10-6 cm2 (20µm diameter) to ~250V at 2.2×10-3 cm-2 (0.53 mm diameter). The current density near breakdown was not strongly dependent on contact circumference but did scale with contact area, indicating the bulk current contribution was dominant. The lowest on-state resistance, Ron, was 1.6 mΩ-cm2 for the largest diode and 25 mΩ.cm2 for the 1600V rectifier, leading to a Baliga figure-of-merit (VBR2/Ron) for the latter of approximately 102.4 MW·cm−2. The on-off ratio was measured at a forward voltage of 1.3V and ranged from 3x107 to 2.5x106 for reverse biases from – 5 to -40 V and showed only a small dependence on temperature in the range 25-100°C. The Schottky barrier height decreased from 1.1 at 25°C to 0.94 eV at 100°C, while the ideality factor increased from 1.08 to 1.28 over the same range. The reverse recovery time was 26 ns for switching from +5V to -5V. These results represent another impressive advance in the quality of bulk and epitaxial β-Ga2O3.