Experimental evidence of wide bandgap in triclinic (001)-oriented Sn5O2(PO4)2 thin films on Y2O3 buffered glass substrates

Sn5O2(PO4)2 is a promising p-type transparent semiconducting oxide. Phase-pure triclinic Sn5O2(PO4)2 thin films were grown by pulsed laser deposition using a Sn2(P2O7) target with higher phosphorus content. The (001)-oriented growth of triclinic Sn5O2(PO4)2 on glass was achieved by means of a (111)-textured Y2O3 buffer layer. STEM-EDX and XPS revealed that the composition of the obtained film is near-stoichiometric, thus indicating a suitable semiconducting material. The bandgap of the triclinic Sn5O2(PO4)2 film was estimated to be as large as 3.87 eV, which is the first experimental evidence verifying a recent theoretical prediction by Q. Xu et al., Chem. Mater., 2017, 29, 2459 quite closely.