Adsorption-controlled growth and electronic transport properties of La-doped CaSnO₃ films

The alkaline earth stannates are touted for their wide band gaps and the highest room-temperature electron mobilities among all perovskite oxides. CaSnO₃ has the highest measured band gap in this family and is thus a particularly promising ultra-wide band gap semiconductor. Here we demonstrate the first molecular beam epitaxy (MBE) growth study of epitaxial CaSnO₃ films. By using hybrid MBE, which provides an adsorption-controlled growth window, and a GdScO₃ substrate, which provide a template that closely matched the lattice parameters, we demonstrate the coherent growth of epitaxial CaSnO₃ films. By introducing lanthanum as a dopant, we demonstrate robust and predictable doping of CaSnO₃. Finally, we show the first ever field-effect transistor that use CaSnO₃ as a channel material. This work opens the door to many future studies on the semiconducting properties of CaSnO₃ and the many devices that could benefit from CaSnO₃’s ultra-wide band gap.