Field effect transistors based on α-MoO3 exfoliated crystals: fabrication, functionalization and characterization

Abstract

α-MoO3 field effect transistors (FETs), exhibiting n-type behavior, are fabricated. These devices are based on α-MoO3 exfoliated crystals, which are produced from bulk crystals by mechanical exfoliation and then transferred onto Si/SiO2 substrates, through a two-step clean transfer process. The FET devices are then achieved by depositing three electrical contacts in a bottom-gate geometry, using photolithography, metal sputtering deposition, and lift-off. Thermal treatments in different atmospheres (vacuum and air) are performed to tune the electrical properties of the channel material by controlling the oxygen vacancy concentration. Preliminary electrical characterization of a modified device reveals a modulation of channel resistance with the gate bias, in agreement with the characteristic n-type behavior of α-MoO3. Notably, it exhibits a promising electron mobility value of ≈0.117 cm2 V−1 s−1, which is comparable to values reported for n-type FETs based on a single/few atomic layers of α-MoO3 and MoS2. Additionally, the transfer curves exhibit anticlockwise hysteresis effects, likely attributed to the adsorption/desorption processes of oxygen molecules on the channel surface, promoted by the applied gate voltage.