前驱B膜沉积时间对MgB_2薄膜超导特性的影响

The influence of deposition precursor B films' time on the superconducting properties of MgB_2 films

利用化学气相沉积法(CVD)在多晶Al2O3衬底上制备出了系列MgB2超导薄膜,研究了前驱硼膜沉积时间对MgB2薄膜超导特性的影响,通过XRD、SEM和R-T曲线对超导MgB2薄膜进行了表征。延长前驱硼膜的沉积时间,得到的硼膜结晶度越高,结构更致密。经退火后制备的MgB2薄膜表面富余的Mg可以改善晶粒间的连接,提升T c值。该实验沉积10min前驱硼膜得到的MgB2超导薄膜T c值为34K,且超导转变宽度比较窄。延长前驱硼膜沉积时间到15min后,薄膜的T c值降低,这是由于前驱硼膜较多,Mg和硼反应不充分所导致的。

The MgB2 superconducting films ware been synthesized on polycrystalline AI203 substrates by chemistry vapor deposition technique. The films were characterized by XRD, SEM and R - T curve. Prolonging the deposition time of the precur- sor boron film, the obtained film was more compact and better crystallinity. In addition, the overage Mg presence in MgB2 films would improve the connection of the grains and enhanced the T＋ value. The optimum deposition time of boron precursor films showed ten minutes, the superconducting film T＋ value was 34K, and the superconducting transition width was narrow. Prolonging the deposition time of boron film, the Tc value would decrease. This was due to Mg and boron reaction inefficient.