Microstructure of MgB 2 thin film deposited on r-plane sapphire substrate by co-evaporation method

• Published in: Physica. C, Superconductivity Vol. 469; no. 15; pp. 1571 - 1573
• Main Authors: Kang, S.G., Park, S.C., Chung, J.-K., Jeong, D.G., Kim, C.-J., Kim, C.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2009
• Subjects: MgB 2; TEM; Thin film; 74.70.Ad; MgB 2; TEM; 74.78.Db; Thin film
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2009.05.221

The microstructural features of MgB 2 thin film deposited by co-evaporation method have been investigated by transmission electron microscopy (TEM). MgB 2 thin films were deposited on r-plane sapphire substrate. The critical temperature of this film was measured to be ∼28 K with Δ T c of about 5 K. XRD data reveal that MgO is the major second-phase in MgB 2 film. The surface morphologies have been observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Cross-sectional TEM images also showed that the MgB 2 thin films deposited on r-plane sapphire substrate contained secondary phase such as MgO. Besides, according to the results of selected-area electron diffraction (SAD) patterns and high-resolution TEM (HRTEM) images, the MgB 2 thin films deposited on the r-plane sapphire substrate comprised minor amount of the amorphous phase regions. The structural features of second-phase such as MgO and amorphous phase, crystal orientation across the interface, and defects in the cross-sectional direction were characterized with STEM-EDS and HRTEM. The correlation between superconducting properties and the MgB 2 thin films microstructures are briefly discussed.