Amorphous Ta2SnO6: A hole-dopable p-type oxide

Recent research work on searching for high mobility p-type oxides has identified substantial promising p-type oxide candidates. However, very few of them have been experimentally proven with high p-type conductivity, due to their limited p-type dopability caused by the deep valence band edge (VBE). In this work, we report amorphous phase Ta2SnO6 (a-Ta2SnO6) possessing unusually shallow VBE that permits high p-type doping without hole-killing oxygen vacancy defects spontaneous formation, contrasting to crystalline Ta2SnO6 (c-Ta2SnO6). The shallow VBE in a-Ta2SnO6 also allows a low Schottky barrier height with contact metals and unique a−/c- Ta2SnO6 heterostructure device. The shallow VBE in a-Ta2SnO6 is due to the local structure disorder that circumvents the strong electrostatic Coulombic interaction between positively charged Ta5+ and Sn-5 s lone-pair electrons which accounts for the deep VBE and low p-type dopability in c-Ta2SnO6.