High electron mobility in heavily sulfur-doped 4H-SiC

The Hall electron mobility in sulfur-doped 4H-SiC over a wide range of S concentration was investigated. Sulfur (S) works as a double donor in SiC. The electron concentration in the S+-implanted layers saturates when the S concentration exceeds 1×1018 cm−3 and the net donor concentration of the S+-implanted layer with S concentration of 1×1019 cm−3 is 4×1018 cm−3, indicating that the solubility or activation limit of S+-implanted SiC is about 2×1018 cm−3. The S+-implanted SiC with a S concentration of 1×1018 cm−3 exhibits an electron mobility of 598 cm2/V s, which is more than twice as high as that in N-doped SiC with the same doping concentration (268 cm2/V s). The temperature dependence of the electron mobility in S+-implanted SiC is reproduced in the wide temperature range by the calculation of the electron mobility adopting the helium atom model for neutral-impurity scattering.