Theoretical and experimental approaches for the determination of functional properties of MgSnN₂ thin films

MgSnN₂ thin films were deposited by reactive magnetron co-sputtering on fused silica and silicon substrates. The properties of the films were determined as a function of the deposition temperature. Although the films exhibited a strong preferred orientation along the [002] direction, cumulative X-ray diffractograms at various χ angles evidenced that the deposited films crystallized in a wurtzite-like structure. Regardless of the substrate temperature during deposition, MgSnN₂ films had a columnar microstructure. Mössbauer spectrometry and X-ray photoemission spectroscopy were used to extract the chemical environment of magnesium and tin atoms and to identify their oxidation states. Electrical properties were deduced from Hall effect measurements. An increase of the electron mobility was noticed at high deposition temperature. The optical band gap of MgSnN₂ films increased from approx. 2.28 to 2.43 eV in the 300–500 °C range. The experimental optical properties of MgSnN₂ films were compared to those obtained by ab initio calculations.