Evaluation of tin nitride (Sn 3 N 4 ) via atomic layer deposition using novel volatile Sn precursors

Novel Sn precursors, Sn(tbip) 2 , Sn(tbtp) 2 , and Sn(tbta) 2 , were synthesized and characterized using various analytical techniques and density functional theory calculations. These precursors contained cyclic amine ligands derived from iminopyrrolidine. X-ray crystallography revealed the formation of monomeric SnL 2 with distorted seesaw geometry. Thermogravimetric analysis demonstrated the exceptional volatility of all complexes. Sn(tbtp) 2 showed the lowest residual weight of 2.7% at 265 °C. Sn 3 N 4 thin films were successfully synthesized using Sn(tbtp) 2 as the Sn precursor and NH 3 plasma. The precursor exhibited ideal characteristics for atomic layer deposition, with a saturated growth per cycle value of 1.9 Å cy −1 and no need for incubation when the film was deposited at 150–225 °C. The indirect optical bandgap of the Sn 3 N 4 film was approximately 1–1.2 eV, as determined through ultraviolet–visible spectroscopy. Therefore, this study suggests that the Sn 3 N 4 thin films prepared using the newly synthesized Sn precursor are suitable for application in thin-film photovoltaic devices.