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Stacking single layers of atoms on top of each other provides a fundamental way to achieve novel material systems and engineer their physical properties, which offers opportunities for exploring fundamental physics and realizing next-generation optoelectronic devices. Among the two-dimensional (2D)-stacked systems, transition metal dichalcogenide (TMDC) heterostructures are particularly attractive because they host tightly-bonded interlayer excitons which possess various novel and appealing properties. These interlayer excitons have drawn significant research attention and hold high potential for the application in unique optoelectronic devices, such as polarization- and wavelength-tunable single photon emitters, valley Hall transistors, and possible high-temperature superconductors. The development of these devices requires a comprehensive understanding of the fundamental properties of these interlayer excitons and the impact of electric fields on their behaviors. In this review, we summarize the recent advances on the understanding of interlayer exciton dynamics under electric fields in TMDC heterostructures. We put emphasis on the electrical modulation of interlayer excitons' emission, the valley Hall transport of charge carriers after the separation of interlayer excitons by an electric field, and the correlation physics of interlayer excitons and charges under electrical doping and tuning. Challenges and perspectives are finally discussed for the application of TMDC heterostructures in future optoelectronics. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW) heterostructures—in which layered materials are purposely selected to assemble with each other—allow unusual properties and different phenomena to be combined and multifunctional electronics to be created, opening a new chapter for the spread of internet‐of‐things applications. Here, an O2‐ultrasensitive MoTe2 material and an O2‐insensitive SnS2 material are integrated to form a vdW heterostructure, allowing the realization of charge‐polarity control for multioperation‐mode transistors through a simple and effective rapid thermal annealing strategy under dry‐air and vacuum conditions. The charge‐polarity control (i.e., doping and de‐doping processes), which arises owing to the interaction between O2 adsorption/desorption and tellurium defects at the MoTe2 surface, means that the MoTe2/SnS2 heterostructure transistors can reversibly change between unipolar, ambipolar, and anti‐ambipolar transfer characteristics. Based on the dynamic control of the charge‐polarity properties, an inverter, output polarity controllable amplifier, p‐n diode, and ternary‐state logics (NMIN and NMAX gates) are demonstrated, which inspire the development of reversibly multifunctional devices and indicates the potential of 2D materials. [ABSTRACT FROM AUTHOR]

Atomically thin tungsten diselenide (WSe2) transistors with multilayer graphene (w/ G) as contact electrodes are successfully fabricated by a precise area‐controllable chemical vapor deposition method. The performance and electrical properties of the devices are explored. Compared to those of WSe2 transistors without graphene contacts (w/o G), the maximum current densities of the w/ G–WSe2 transistors increase by one to two orders of magnitude. In addition, the device performance is markedly improved for the w/ G–WSe2 transistors, including an on/off current ratio of ≈107, subthreshold swing of ≈150 mV/decade, and threshold voltage of ≈1.75 V. The improved performance of the w/ G–WSe2 transistors is ascribed to the alleviation of electrical contributions from metal–semiconductor contact resistance, which is consistent with the analysis of low‐frequency noise measurements. In addition, self‐trapping behavior in the WSe2 channel is found, which possibly paves a way to further optimize the performance of layered devices. Finally, an inverter using the w/ G–WSe2 transistors is demonstrated. These transistors represent a step forward in the development of layered graphene‐based electronics suitable for energy‐efficient and high‐performance industrial‐scale products. [ABSTRACT FROM AUTHOR]

Recent experiments since the discovery of monolayer graphite or graphene have led to an exciting revival in the interest in the electronic applications for graphene, as well as other 2-D materials such as hexagonal boron nitride (hBN) and molybdenum disulfide (MoS2 ). These layered materials serve as an exciting new platform for flexible and transparent electronics where surfaces can be enriched with new functionality. This paper aims to provide an overview behind these new class of materials ranging upon important issues for electronic integration including synthesis all the way to current state-of-the-art circuits and devices made from these materials. [ABSTRACT FROM PUBLISHER]

Carbon nanotube field effect transistor has attracted much attention recently and is a promising candidate for next generation nanoelectronics. Here, we report our study on a transistor using single wall carbon nanotube network as the channel and a ferroelectric film as the gate dielectric. The spontaneous polarization of ferroelectric materials offers nonvolatility and controllability of the surface charges. Modulation of >102 in the channel conductivity has been observed in the network-based transistor. Voltage pulses are used to control the transistor states; no continuous gate bias is needed. Furthermore, n-type behavior of the network channel is observed, which is attributed to a change in the Schottky barrier at the carbon nanotube-metal interface. [ABSTRACT FROM AUTHOR]

A solution processable method for employing single-walled carbon nanotubes (SWCNTs) as bottom contact source/drain electrodes for a significant reduction of contact resistance in poly(3,3‴-didodecylquarterthiophene) based organic field effect transistors (OFETs) is proposed. A two order of magnitude reduction in contact resistance and up to a threefold improvement in field effect mobilities were observed in SWCNT contacted OFETs as opposed to similar devices with gold source/drain electrodes. Based on Kelvin probe measurements, this improvement was attributed to a reduction in the Schottky barrier for hole injection into organic semiconductor. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials, such as molybdenum disulfide (MoS2), have been shown to exhibit excellent electrical and optical properties. The semiconducting nature of MoS2 allows it to overcome the shortcomings of zero-bandgap graphene, while still sharing many of graphene's advantages for electronic and optoelectronic applications. Discrete electronic and optoelectronic components, such as field-effect transistors, sensors, and photodetectors made from few-layer MoS2 show promising performance as potential substitute of Si in conventional electronics and of organic and amorphous Si semiconductors in ubiquitous systems and display applications. An important next step is the fabrication of fully integrated multistage circuits and logic building blocks on MoS2 to demonstrate its capability for complex digital logic and high-frequency ac applications. This paper demonstrates an inverter, a NAND gate, a static random access memory, and a five-stage ring oscillator based on a direct-coupled transistor logic technology. The circuits comprise between 2 to 12 transistors seamlessly integrated side-by-side on a single sheet of bilayer MoS2. Both enhancement-mode and depletion-mode transistors were fabricated thanks to the use of gate metals with different work functions. [ABSTRACT FROM AUTHOR]