The unique structural features of many ternary nitride materials with strong chemical bonding and band gaps above 2.0 eV are limited and are experimentally unexplored. It is important to identify candidate materials for optoelectronic devices, particularly for light-emitting diodes (LEDs) and absorbers in tandem photovoltaics. Here, we fabricated MgSnN2 thin films, as promising II-IV-N2 semiconductors, on stainless-steel, glass, and silicon substrates via combinatorial radio-frequency magnetron sputtering. The structural defects of the MgSnN2 films were studied as a function of the Sn power density, while the Mg and Sn atomic ratios remained constant. Polycrystalline orthorhombic MgSnN2 was grown on the (120) orientation within a wide optical band gap range of ∼2.20-2.17 eV. The carrier densities of 2.18× 1020 to 1.02 × 1021 cm-3, mobilities between 3.75 and 2.24 cm2/Vs, and a decrease in resistivity from 7.64 to 2.73 × 10-3 Ω cm were confirmed by Hall-effect measurements. These high carrier concentrations suggested that the optical band gap measurements were affected by a Burstein-Moss shift. Furthermore, the electrochemical capacitance properties of the optimal MgSnN2 film exhibited an areal capacitance of 152.5 mF/cm2 at 10 mV/s with high retention stability. The experimental and theoretical results showed that MgSnN2 films were effective semiconductor nitrides toward the progression of solar absorbers and LEDs.
Keywords: MgSnN2 ternary nitrides; RF magnetron sputtering; electrochemical capacitance; light-emitting diodes; optoelectronic; solar absorber.