Cross-sectional TEM study and film thickness dependence of Tc in heavily boron-doped superconducting diamond

The film thickness dependence of Tc in heavily B-doped diamond (1 1 1) and (0 0 1) films was investigated and cross-sectional transmission electron microscope observation was employed to investigate the crystalline structure of heavily B-doped diamond. (1 1 1) films with 5 nm or more and (0 0 1) films with 40 nm or more show superconducting transition. Few dislocations are observed in 500 nm from the interface between the substrate and B-doped homoepitaxial layer in (1 1 1) film and defective structure observed in (0 0 1) film.