Flexible p-Type WSe Transistors with Alumina Top-Gate Dielectric.

Tungsten diselenide (WSe) field-effect transistors (FETs) are promising for emerging electronics because of their tunable polarity, enabling complementary transistor technology, and their suitability for flexible electronics through material transfer. In this work, we demonstrate flexible p-type WSe FETs with absolute drain currents || up to 7 μA/μm. We achieve this by fabricating flexible top-gated FETs with a combined WSe and metal contact transfer approach using WSe grown by metal-organic chemical vapor deposition on sapphire.

Biaxial Strain Transfer in Monolayer MoS and WSe Transistor Structures.

Monolayer transition metal dichalcogenides are intensely explored as active materials in 2D material-based devices due to their potential to overcome device size limitations, sub-nanometric thickness, and robust mechanical properties. Considering their large band gap sensitivity to mechanical strain, single-layered TMDs are well-suited for strain-engineered devices. While the impact of various types of mechanical strain on the properties of a variety of TMDs has been studied in the past, TMD-based devices have rarely been studied under mechanical deformations, with uniaxial strain being the most common one.

Toward Mass Production of Transition Metal Dichalcogenide Solar Cells: Scalable Growth of Photovoltaic-Grade Multilayer WSe by Tungsten Selenization.

Semiconducting transition metal dichalcogenides (TMDs) are promising for high-specific-power photovoltaics due to their desirable band gaps, high absorption coefficients, and ideally dangling-bond-free surfaces. Despite their potential, the majority of TMD solar cells to date are fabricated in a nonscalable fashion, with exfoliated materials, due to the lack of high-quality, large-area, multilayer TMDs. Here, we present the scalable, thickness-tunable synthesis of multilayer WSe films by selenizing prepatterned tungsten with either solid-source selenium at 900 °C or HSe precursors at 650 °C.

Flexible Nanoscale Amorphous Oxide Transistors with a Gold-Assisted Transfer Method.

We present a new approach to achieve nanoscale transistors on ultrathin flexible substrates with conventional electron-beam lithography. Full devices are first fabricated on a gold sacrificial layer covering a rigid silicon substrate, and then coated with a polyimide film and released from the rigid substrate. This approach bypasses nanofabrication constraints on flexible substrates: (i) electron-beam surface charging, (ii) alignment inaccuracy due to the wavy substrate, and (iii) restricted thermal budgets.

Ambipolar Thickness-Dependent Thermoelectric Measurements of WSe.

Thermoelectric materials can harvest electrical energy from temperature gradients, and could play a role as power supplies for sensors and other devices. Here, we characterize fundamental in-plane electrical and thermoelectric properties of layered WSe over a range of thicknesses, from 10 to 96 nm, between 300 and 400 K. The devices are electrostatically gated with an ion gel, enabling us to probe both electron and hole regimes over a large range of carrier densities.