A New Method for Preparing Superconducting MgB2 Films from Diborane

We report on a new preparation method for magnesium diboride (MgB2) films by chemical vapour deposition (CVD) from diborane (B2H6).It is two-step ex situ approach,with the precursor boron films grown by CVD from B2H6 at 460℃,followed by a post-annealing process in magnesium (Mg) vapour at 830℃.The prepared MgB2 thin films on Al2O3 polycrystalline substrates have an onset transition temperature of 35K and a zeroresistance temperature of about 24K.Well-crystallized MgB2 grains have clearly been observed in the SEM images and confirmed by x-ray diffraction analysis.The advantages of the proposed method are the feasibility to prepare large-area superconducting films and the compatibility with semiconductor technology.