Résumé
We report on an investigation of superconductivity in n-type InN. There is an optimum carrier density for the occurrence of the superconductivity. The lowest carrier density is limited by the Mott transition of ne~2×1017cm−3 and the highest density is limited by the superconductor to metal transition of ne~5×1020cm−3. As in the layered cuprate high Tc superconductors, the vortex solid of InN is melted by thermal fluctuation and by the external magnetic field. The field dependence of the critical current Jc exhibits an exponential decay over a wide range of magnetic field, which is ascribed to the current tunneling through micro Josephson-junctions. We propose a mechanism where the anisotropy of Jc is related to the presence of In-In chains of finite length in the ab plane.