α-MoO3 as a Conductive 2D Oxide: Tunable n-Type Electrical Transport via Oxygen Vacancy and Fluorine Doping

Layered transition metal oxides remain a relatively unexplored front in the study of two-dimensional (2D) van der Waals materials, providing opportunities to further advance semiconductor physics and devices in a novel class of atomically thin crystals. It is usually uncommon to observe tunable electronic characteristics or achieve field effect control in these materials, given their wide band gaps and insulating nature. However, when these oxides are manipulated via doping or intercalation with new ion species, the band gap, carrier concentration, and field effect mobility can be affected, as well. Herein, we conduct a study to dope multilayer nanoflakes of α-MoO3 with H+ ion intercalation, which creates oxygen vacancies and facilitates n-type conduction. Devices are characterized with controllable electron densities in the range of 1019–1021/cm3 and field effect gating behavior with typical field effect mobilities of 0.1 cm2/Vs. Furthermore, both wet-etching and dry-etching techniques are conducted to d...