In comparison to monolayer (1L), multilayer (ML) two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) exhibit more application potential for electronic and optoelectronic devices due to their improved current carrying capability, higher mobility, and broader spectral response. However, the investigation of devices based on wafer-scale ML-TMDs is still restricted by the synthesis of uniform and high-quality ML films. In this work, we propose a strategy of stacking MoS₂ monolayers via a vacuum transfer method, by which one could obtain wafer-scale high-quality MoS₂ films with the desired number of layers at will. The optical characteristics of these stacked ML-MoS₂ films (> 2L) indicate a weak interlayer coupling. The stacked ML-MoS₂ phototransistors show improved optoelectrical performances and a broader spectral response (approximately 300–1,000 nm) than that of 1L-MoS₂. Additionally, the dual-gate ML-MoS₂ transistors enable enhanced electrostatic control over the stacked ML-MoS₂ channel, and the 3L and 4L thicknesses exhibit the optimal device performances according to the turning point of the current on/off ratio and the subthreshold swing.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS₂) have been intensively investigated because of their exclusive physical properties for advanced electronics and optoelectronics. In the present work, we study the MoS₂ transistor based on a novel tri-gate device architecture, with dual-gate (Dual-G) in the channel and the buried side-gate (Side-G) for the source/drain regions. All gates can be independently controlled without interference. For a MoS₂ sheet with a thickness of 3.6 nm, the Schottky barrier (SB) and non-overlapped channel region can be effectively tuned by electrostatically doping the source/drain regions with Side-G. Thus, the extrinsic resistance can be effectively lowered, and a boost of the ON-state current can be achieved. Meanwhile, the channel control remains efficient under the Dual-G mode, with an ON-OFF current ratio of 3 × 10⁷ and subthreshold swing of 83 mV/decade. The corresponding band diagram is also discussed to illustrate the device operation mechanism. This novel device structure opens up a new way toward fabrication of high-performance devices based on 2D-TMDs.

A spin-coating method was applied to obtain thinner and smoother PEO/LiClO₄ polymer electrolyte films (EFs) with a lower level of crystallization than those obtained using a drop-casting method. When the applied frequency was as high as 10 kHz, the specific capacitance of such EFs with thicknesses of 1.5 μm was on the order of 1 μF·cm^-2, a value larger than most of the previously reported results achieved from the same material. We then combined the thin EFs with two-dimensional (2D) materials to fabricate a MoS₂ transistor with a top gate right above the channel, defined by a shadow-mask method, and an inverter device. This transistor showed excellent static characteristics and the inverter device showed excellent switching performance at 100 Hz, which indicates a fast polarization response of the thin EFs. Such device architecture is suitable for future low power and flexible electronics based on 2D materials.