Very low resistance ohmic contacts to p-type SiC were fabricated by depositing a 90-10 wt.% alloy of Al and Ti followed by a high temperature anneal of approximately 1000°C for 2 min. Specific contact resistances ranged from approximately 5 × 10-6 to 3 × 10-5 Ω cm2 on material with a doping of 1.3 × 1019 cm-3. The initial Al-Ti thickness before annealing was found to be critical to controlling the Al-Ti sheet resistance during the anneal. In addition, chemically etching the Al-Ti layer after annealing revealed pitting indicative of severe reaction between the Al-Ti and SiC surface, as confirmed by Rutherford Backscattering. In contrast, ohmic contacts to the same SiC material were fabricated by depositing pure Ti and annealing at 800°C for 1 min. These contacts were ohmic with a specific contact resistance between 2 × 10-5 and 4 × 10-5 Ω cm2. Examination of the SiC surface after chemically etching away the annealed contact revealed a smooth surface, suggesting a much more planar Ti/SiC interface.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry