Composition dependent intrinsic defect structures in ASnO₃ (A = Ca, Sr, Ba)

Perovskite stannates are promising semiconductors that are widely used in optoelectronic devices. Here, the composition dependent intrinsic point defects of stannate perovskites ASnO₃ (A = Ca, Sr, Ba) are studied by first-principles calculations. The preferences of defects under stoichiometric and nonstoichiometric conditions are unsealed, meanwhile the charge states of each intrinsic defect varying with the change of electron Fermi energy are clarified. For stoichiometric BaSnO₃ and SrSnO₃, the Schottky defect complexes are predicted as the most stable defect structure, while the antisite defect complexes are the most stable one in CaSnO₃. In nonstoichiometric ASnO₃, excessive AO is beneficial to the formation of oxygen vacancies and A-Sn antisite defects in all ASnO₃; while the Ca interstitial is another major defect existing in CaSnO₃. In the case of SnO₂ excess, the predominant defects are the Sn-A antisite defects and A vacancies. Since the functionality of these perovskite oxides is closely related to the types and concentrations of their point defects, the present results are expected to guide the future experiments to optimize the function of the perovskite oxides by tailoring the intrinsic defects through controlling the composition of AO and SnO₂.