Effects of Processing Condition on the Properties of Fe(Se,Te) Thin Films Grown by Sputtering

We studied the effects of processing conditions on the properties and microstructure of Fe_y(Se_1-xTe_x) thin films grown on MgO substrates by RF sputtering. The thin films were grown in two ways; in situ deposition onto heated substrates and deposition onto cold substrates followed by an ex situ annealing process. Various properties of the deposited Fe(Se,Te) thin films including the phase, texture, surface morphology, composition, and superconducting properties were investigated. The results showed that in situ sputtering leads to higher quality films, e.g., smoother surface, pure phase, more uniform composition, and better crystallographic alignment. For the ex situ grown films, depending on the annealing conditions, phase separation, appearance of the impurity phases such as hexagonal Fe(Se,Te), poor texture, higher Fe-content, nonuniform composition, and rough surfaces developed in the films.