The fabrication and characterization of half-Heusler YPdBi thin films

Abstract

The electrical, optical, and magnetic properties of half-Heusler compounds make them novel interesting materials being studied by many groups worldwide. The synthesis of YPdBi, a member of half-Heusler compounds, thin films have been achieved at different deposition temperatures such as 360 °C and 470 °C by employing magnetron co-sputtering technique. X-ray diffraction (XRD) examinations have revealed that the film deposited at 360 °C has a slightly larger lattice parameter, 6.82 Å, than the film fabricated at 470 °C, having 6.73 Å. The induced strain of the films has been 2.1% and 0.7% for the films deposited at 360 °C and 470 °C, respectively. X-ray photoelectron spectroscopy (XPS) investigations have revealed the obtained films have the stoichiometry close to the 1:1:1 ratio. Scanning electron microscopy (SEM) studies have shown that surface topography varies dramatically as the deposition temperature advances. Furthermore, high-resolution scanning transmission electron microscopy (STEM) has shown that layer-plus-island growth known as the Stranski–Krastanov (SK) growth mode, taking place due to minimization of strain energy, leads to the island formation from a specific film thickness on. It has been shown that while the resistance of the sample grown at 470 °C changes abruptly at 2.45 K, which indicates the onset of superconductivity, the sample deposited at 360 °C does not show this effect. The absence of the onset of superconductivity in this latter case might be associated with the lattice strain and intensive scattering in this sample.