Divalent Path to Enhance p-Type Conductivity in a SnO Transparent Semiconductor

The role of the divalent nature of tin is explored in tin monoxide, revealing a novel path for enhancing p-type conductivity. The consequences of oxygen off-stoichiometry indicate that a defect complex formed by a tin vacancy (V-Sn) and an impurity interstitial (D-i) leads to an increased number of free carriers as well as improved acceptor state stability when compared with the isolated V-Sn. In this study, we identify several elements that are able to stabilize such a defect complex configuration. The enhanced ionization of the resulting complex arises from the divalent nature of Sn, which allows Sn(II) and Sn(IV) oxidation states to form. Such a novel doping mechanism not only offers a path for creating a high-performance p-type transparent SnO, but reveals an as-of-yet unexplored route to improve conductivity in other compounds formed by multivalent elements, for example, Sn(II)-based thermoelectrics.