Fabrication and characterization of superconducting MgB 2 thin films grown by rf sputtering and thermal evaporation method

Abstract

We have grown MgB 2 thin films by co-deposition method. Magnesium (Mg) and Boron (B) were simultaneously deposited on the substrates using the radio frequency (rf) sputtering and thermal evaporation. The deposition conditions were varied by changing Mg evaporation rate, B sputtering rate, substrate temperature, deposition time, and types of substrates ( c-Al 2O 3, r-Al 2O 3, LaAlO 3, MgO). The MgB 2 layers had 400–500 nm in thickness and occasionally MgB 12 was formed as a second phase. Superconducting transition temperatures have been measured around 20–37 K depend on the types of substrates and growth conditions. The relative deposition rate of Mg and B was important to maintain the stoichiometry of MgB 2. The structural features such as second phases, crystal orientation across the interface, and defects in the cross-sectional direction were characterized with XRD, SEM, and EDS.