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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 × 10 18 cm − 3 and the net donor concentration of the S + -implanted layer with S concentration of 1 × 10 19 cm − 3 is 4 × 10 18 cm − 3 , indicating that the solubility or activation limit of S + -implanted SiC is about 2 × 10 18 cm − 3 . The S + -implanted SiC with a S concentration of 1 × 10 18 cm − 3 exhibits an electron mobility of 598 cm 2 /V s, which is more than twice as high as that in N-doped SiC with the same doping concentration (268 cm 2 /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. [ABSTRACT FROM AUTHOR]

In this work, the distribution and segregation behaviors of helium (He) and the effect of yttrium (Y) on these behaviors in the symmetrical tilt tungsten (W) Σ5(310)/[001] grain boundary (GB) region were studied using first-principles calculations. The results revealed that the GB has a significant impact on the behaviors of He in W. The solution and segregation energies of He in the W Σ5(310)/[001] GB region increase with increasing the distance from He to the GB and are inversely proportional to the effective electrons of He. The density of states analysis showed that the GB can suppress partial hybridization between He and W atoms. In addition, we find that the strengthening element Y facilitates the dissolution of He in the W GB region. [ABSTRACT FROM AUTHOR]