Effects of Cr interlayer thickness on adhesive, structural, and thermoelectric properties of antimony telluride thin films deposited by radio-frequency magnetron sputtering

We investigated the effects of Cr interlayer thickness on adhesive, structural, and thermoelectric properties of p-type antimony telluride (Sb2Te3) thin films. Prior to depositing Sb2Te3 films with a thickness of 1 μm using radio-frequency magnetron sputtering, a Cr film with a thickness ranging from 0 to 216 nm was deposited on a glass substrate using the same sputtering equipment. The obtained samples were thermally annealed at 300 °C for 1 h. Adhesiveness of the films was examined by a cross-cut method. Adhesion of Sb2Te3 thin films could be improved by incorporating the Cr interlayer, independent of the thickness of the interlayer. The surface morphology of the Sb2Te3 thin films became flat with a dense structure as the thickness of the Cr interlayer increased. Atomic composition analysis indicated that Te atoms might be diffused into the Cr interlayer and formed Cr-based alloys when the Cr interlayer thickness was increased to > 100 nm. X-ray diffraction analyses indicated that the crystal orientation, crystallite size, and strain of the films reached their maximum values at Cr interlayer thicknesses of 46-70 nm. Thermoelectric properties of the films were improved by incorporating the Cr interlayer of appropriate thickness. In particular, a power factor of 18.7 μW/(cm K2) was achieved at a Cr interlayer thickness of 46 nm, which was approximately 4 times larger than that of the film with no Cr interlayer.