Superconductivity in carrier-doped silicon carbide

Abstract

We report growth and characterization of heavily boron-doped 3C-SiC and 6H-SiC and Al-doped 3C-SiC. Both 3C-SiC:B and 6H-SiC:B reveal type-I superconductivity with a critical temperature <i>T</i>_c=1.5 K. On the other hand, Al-doped 3C-SiC (3C-SiC:Al) shows type-II superconductivity with <i>T</i>_c=1.4 K. Both SiC:Al and SiC:B exhibit zero resistivity and diamagnetic susceptibility below <i>T</i>_c with effective hole-carrier concentration <i>n</i> higher than 10²⁰ cm^-3. We interpret the different superconducting behavior in carrier-doped <i>p</i>-type semiconductors SiC:Al, SiC:B, Si:B and C:B in terms of the different ionization energies of their acceptors.