热丝化学气相沉积法原位制备的MgB_2超导薄膜

MgB_2 Superconducting Films in Situ Prepared by Hot-Filament Chemical Vapor Deposition

用热丝化学气相沉积法(HFCVD)在蓝宝石基片上原位制备了MgB2超导薄膜,并用XRD、SEM和dcSQUIDs研究了基片温度和时间对薄膜相组成、表面形貌和超导临界转变温度Tc的影响。结果表明,HFCVD原位生长MgB2薄膜可以抑制MgO杂质的生成。基片温度在500℃以下,MgB4杂相容易出现;在500℃以上时,可以消除MgB4杂相;在600℃时,获得了纯单相的MgB2薄膜,其超导临界转变温度达到36K。随基片温度升高,薄膜结晶性、致密度和超导临界转变温度提高。

MgB2 superconducting effects of substrate temperature temperature Tc of the films were films were in situ prepared and deposition time on the studied by X-ray diffraction, on sapphire substrates by hot-filament chemical vapor deposition. The phase component, surface morphology, and superconducting transition scanning electron microscopy, and dc SQUIDs. The experimental results showed that no MgO impurities form in the MgB2 films grown by this method and the MgB4 inclusions easily form when the substrate temperature is lower than 500 ℃. The single-phase MgB2 film with Tc=36 K can be obtained at 600 ℃. The crystallinity, densification and Tc of the films can be enhanced as the substrate temperature increasing.