Electronic structure of superconducting InN

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 insulator transition of ne∼5×1020cm-3. We propose a mechanism where the occurrence of the superconductivity is related to the presence of In-In chains of finite length in the ab plane. The In-In chains, which originate from the inversion domains of InN grown on sapphire (0 0 0 1) and elongate along [112¯0], are coupled to form micro Josephson-junctions.