Harnessing Selective Exsolution of Sn Metal to Enhance Electrical Conductivity in Oxygen-Deficient Perovskite Stannates

The versatile application of newly discovered oxide semiconductors calls for developing a simple process to generate conducting carriers. High-temperature reduction treatment leads to electrical conduction in perovskite stannate semiconductors, but carrier concentration is poorly controlled and inconsistently reported in BaSnO3-delta films after the reduction process so far. Here, a new strategy to enhance the electrical conductivity of BaSnO3-delta films is demonstrated by exploiting selective exsolution of Sn metals in the perovskite framework. Due to strong dependence of conductivity on initial Sn/Ba cation ratio in the reduced BaSnO3-delta films, interestingly, only Sn-excess BaSnO3-delta films show a dramatic increase of carrier concentration ( increment n(3D) = 5-7 x 10(19) cm(-3)) after high-temperature reduction; exceptionally high electrical conductivity (sigma approximate to 6000 S cm(-1)) is achieved in reduced Sn-excess (La, Ba)SnO3-delta films, which exceed full activation of La dopants in untreated (La, Ba)SnO3. By multiple characterizations combined with theoretical calculation, it is disclosed that a small fraction of segregated beta-Sn nanoparticles is likely to contribute the additional source of n(3D) in the BaSnO3-delta matrix as a result of spontaneous charge transfer from the segregated beta-Sn metallic phase to BaSnO3-delta. These original results propose a simple strategy to further increase electrical conductivity in perovskite oxide semiconductors by non-stoichiometry-driven metal exsolution.

Automated summary

A simple strategy to increase electrical conductivity in perovskite oxide semiconductors has been proposed through non-stoichiometry-driven metal exsolution, leading to enhanced carrier concentration in reduced films.