  The discoveries of superconductivity in the heavily-boron doped
semiconductors diamond (C:B) in 2004 and silicon (Si:B) in 2006 have renewed
the interest in the physics of the superconducting state of doped
semiconductors. Recently, we discovered superconductivity in the closely
related ''mixed'' system heavily boron-doped silcon carbide (SiC:B).
Interestingly, the latter compound is a type-I superconductor whereas the two
aforementioned materials are type-II. In this paper we present an extensive
analysis of our recent specific-heat study, as well as the band structure and
expected Fermi surfaces. We observe an apparent quadratic temperature
dependence of the electronic specific heat in the superconducting state.
Possible reasons are a nodal gap structure or a residual density of states due
to non-superconducting parts of the sample. The basic superconducting
parameters are estimated in a Ginzburg-Landau framework. We compare and discuss
our results with those reported for C:B and Si:B. Finally, we comment on
possible origins of the difference in the superconductivity of SiC:B compared
to the two ''parent'' materials C:B and Si:B.
