Epitaxial growth and characterization of high quality Bi 2 O 2 Se thin films on SrTiO 3 substrates by pulsed laser deposition

Recently, Bi 2 O 2 Se was revealed as a promising two-dimensional (2D) semiconductor for next generation electronics, due to its moderate bandgap size, high electron mobility and pronounced ambient stability. Meanwhile, it has been predicted that high-quality Bi 2 O 2 Se-related heterostructures may possess exotic physical phenomena, such as piezoelectricity and topological superconductivity. Herein, we report the first successful heteroepitaxial growth of Bi 2 O 2 Se films on SrTiO 3 substrates via pulsed laser deposition (PLD) method. Films obtained under optimal conditions show an epitaxial growth with the c axis perpendicular to the film surface and the a and b axes parallel to the substrate. The growth mode transition to three-dimensional (3D) island from quasi-2D layer of the heteroepitaxial Bi 2 O 2 Se films on SrTiO 3 (001) substrates is observed as prolonging deposition time of films. The maximum value of electron mobility reaches 160 cm 2 V −1 s −1 at room temperature in a 70 nm thick film. The thickness dependent mobility provides evidence that interface-scattering is likely to be the limiting factor for the relatively low electron mobility at low temperature, implying that the interface engineering as an effective method to tune the low temperature electron mobility. Our work suggests the epitaxial Bi 2 O 2 Se films grown by PLD are promising for both fundamental study and practical applications.