Thermal stability and polymorphic transformation kinetics in β-MnTe films deposited via radiofrequency magnetron sputtering

Abstract

Abstract A manganese telluride (MnTe) compound is an interesting polymorphic semiconductor with physical properties differing greatly among various polymorphs. In this study, the thermal stability and polymorphic transformation kinetics in β-MnTe films obtained via radiofrequency magnetron sputtering were investigated. The obtained MnTe films with a composition range of 50.5–46.1 at.% Te exhibited a single β phase. The polymorphic transformation temperature from the β (wurtzite-type) to an α (NiAs-type) phase decreased with increasing the Te content. In the non-isothermal analysis using differential scanning calorimetry, the activation energy for β → α transformation was measured to be 1.41 eV, based on Kissinger plots. The retention time of β-MnTe was also investigated via the Ozawa method, and it was estimated to be retained for 4.5 × 109 years at 25 °C. The estimated Avrami exponent of 3.5 indicated that two- and three-dimensional growth at a constant nucleation rate was dominant at the intermediate stage of β → α transformation.