The dc performance of SiO2 dielectric overlap-terminated 4H-SiC Schottky rectifiers was simulated for different drift layer doping levels and dielectric thicknesses. The devices were then fabricated with different Schottky contact diameters and the dc results compared to the simulations. There was a strong dependence of reverse breakdown voltage on contact diameter (φ) ranging from -750 V for 100 μm φ to -440 V for 1000 μm. The reverse leakage current scaled with diode diameter, indicating that the surface contributions are dominant. The specific on-state resistance was ∼0.8 mΩ cm2, close to the theoretical minimum, with a forward turn-on voltage of 2.14 V at 100 A cm-2. The rectifiers were tested to maximum forward currents of 2 A. The contact resistivity of back-side Ni contacts annealed at 970°C was ∼1.2 × 10-6 Ω cm2. The yield of diodes with breakdown >750 V was >50% over a quarter of a 2 in. diam wafer.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry