Surface Charge Transfer Doping via Transition Metal Oxides for Efficient p-Type Doping of II–VI Nanostructures

Wide band gap II–VI nanostructures are important building blocks for new-generation electronic and optoelectronic devices. However, the difficulty of realizing p-type conductivity in these materials via conventional doping methods has severely handicapped the fabrication of p–n homojunctions and complementary circuits, which are the fundamental components for high-performance devices. Herein, by using first-principles density functional theory calculations, we demonstrated a simple yet efficient way to achieve controlled p-type doping on II–VI nanostructures via surface charge transfer doping (SCTD) using high work function transition metal oxides such as MoO 3, WO 3, CrO 3, and V 2 O 5 as dopants. Our calculations revealed that these oxides were capable of drawing electrons from II–VI nanostructures, leading to accumulation of positive charges (holes injection) in the II–VI nanostructures. As a result, Fermi levels of the II–VI nanostructures were shifted toward the valence band regions after surface modifications, along with the large enhancement of work functions. In situ ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy characterizations verified the significant interfacial charge transfer between II–VI nanostructures and surface dopants. Both theoretical calculations and electrical transfer measurements on the II–VI nanostructure-based field-effect transistors clearly showed the p-type conductivity of the nanostructures after surface modifications. Strikingly, II–VI nanowires could undergo semiconductor-to-metal transition by further increasing the SCTD level. SCTD offers the possibility to create a variety of electronic and optoelectronic devices from the II–VI nanostructures via realization of complementary doping.