Preparation of MgB2 Superconducting Thin Films at Low Temperature

MgB2 superconducting thin films have been fabricated on Silicon (111) substrate in a two-step ex situ approach. The precursor boron film was deposited by chemical vapor deposition by using diborane as the boron source at 460°C．The Magnesium film with a thickness of about 380nm was deposited on top of the boron film by magnetron sputtering. The samples were then post-annealed in situ in argon atmosphere at 500°C for time range from 2.5h to 5.0h. The sample for optimized annealing time exhibits abrupt superconducting transition, with an onset temperature around 35K and a zero resistance temperature greater than 34K. The microstructures and morphological properties of the films were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM).