Low temperature Cu/Ti/Al Ohmic contacts to p-type 4H-SiC

In this paper, we studied the electrical and structural properties of Cu/Ti/Al Ohmic contacts to p-type 4 H-SiC with different annealing temperatures and Cu layer thicknesses. Compared with Ti/Al contact annealed at 900–1000 ℃ to form ohmic contact, Cu/Ti/Al contact forms ohmic contact (1.0 ×10⁻⁴ Ω·cm²) after annealing at 800 °C. When the annealing temperature is 850 ℃ and 900 ℃, the contact resistivity of Cu/Ti/Al contact is about 5.4 × 10⁻⁵ Ω·cm². Scanning Electron Microscopy (SEM) is used to observe the surface morphology of the sample. With the increase of annealing temperature, the roughness of the sample surface and the number of pits continue to increase. X-ray spectra shows that the addition of Cu makes the contact form Ti₃SiC₂ at a lower annealing temperature which is the key to low contact resistivity.