Cleaning of SiC surfaces by low temperature ECR microwave hydrogen plasma

N-type 4H-SiC (0 0 0 1) surfaces were cleaned by low temperature hydrogen plasma in electronic cyclotron resonance (ECR) microware plasma system. The effects of the hydrogen plasma treatment (HPT) on the structure, chemical and electronic properties of surfaces were characterized by in situ reflection high energy electron diffraction (RHEED) and X-ray photoelectron spectroscopy (XPS). The RHEED results indicate that the structures of the films are strongly dependent on the treatment temperature and time. Significant improvements in quality of 4H-SiC films can be obtained with the temperature ranging from 200 °C to 700 °C for an appropriate treatment period. The XPS results show that the surface oxygen is greatly reduced and the carbon contamination is completely removed from the 4H-SiC surfaces. The hydrogenated SiC surfaces exhibit an unprecedented stability against oxidation in the air. The surface Fermi level moves toward the conduction band in 4H-SiC after the treatment indicating an unpinning Fermi level with the density of surfaces states as low as 8.09 × 1010 cm−2 eV−1.

► SiC wafers were exposed to low temperature ECR microwave hydrogen plasma. ► The RHEED patterns show that well cleaned, atomically ordered, unreconstructed 4H-SiC surfaces are achieved. ► The Si2p and O1s spectra indicate that the surface oxygen is greatly reduced and the surfaces exhibit stability against oxidation in air. ► The removal of carbon contamination from the SiC surfaces is confirmed by C1s spectrum. ► The hydrogenated SiC surfaces are chemically and electrically well passivated with the density of surfaces states as low as 8.09 × 1010 cm−2 eV−1.