This work demonstrates a mixed-dimensional piezoelectric-gated transistor in the microscale that could be used as a millinewton force sensor. The force-sensing transistor consists of 1D piezoelectric zinc oxide (ZnO) nanorods (NRs) as the gate control and multilayer tungsten diselenide (WSe2) as the transistor channel. The applied mechanical force on piezoelectric NRs can induce a drain-source current change (ΔIds) on the WSe2 channel. The different doping types of the WSe2 channel have been found to lead to different directions of ΔIds. The pressure from the calibration weight of 5 g has been observed to result in an ∼30% Ids change for ZnO NRs on the p-type doped WSe2 device and an ∼-10% Ids change for the device with an n-type doped WSe2. The outcome of this work would be useful for applications in future human-machine interfaces and smart biomedical tools.
Keywords: 2D materials; ZnO nanorods; force sensors; low dimensional materials; piezo-gated field-effect transistors; piezoelectric effect.