Fabrication of a Nb-Doped β-Ga2O3 Nanobelt Field-Effect Transistor and Its Low-Temperature Behavior.

For the first time, we report the successful fabrication of well-behaved field-effect transistors based on Nb-doped β-Ga2O3 nanobelts mechanically exfoliated from bulk single crystals. The exfoliated β-Ga2O3 nanobelts were transferred onto a purified surface of the 110 nm SiO2/Si substrate. These Nb-doped devices showed excellent electrical performance such as an ultrasmall cutoff current of ∼10 fA, a high current on/off ratio of >108, and a quite steep subthreshold swing (SS, ∼120 mV/decade). Furthermore, we investigated the temperature dependence down to 200 K, providing insightful information for its operation in a harsh environment. This work lays a foundation for wider application of Nb-doped β-Ga2O3 in nano-electronics.