Gate Modulation of Threshold Voltage Instability in Multilayer InSe Field Effect Transistors

We report a modulation of threshold voltage instability of back-gated multilayer InSe FETs by gate bias stress. The performance stability of multilayer InSe FETs is affected by gate bias polar, gate bias stress time and gate bias sweep rate under ambient conditions. The on-current increases and threshold voltage shifts to negative gate bias stress direction with negative bias stress applied, which are opposite to that of positive bias stress. The intensity of gate bias stress effect is influenced by applied gate bias time and the sweep rate of gate bias stress. The behavior can be explained by the surface charge trapping model due to the adsorbing/desorbing oxygen and/or water molecules on the InSe surface. This study offers an opportunity to understand gate bias stress modulation of performance instability of back-gated multilayer InSe FETs and provides a clue for designing desirable InSe nanoelectronic and optoelectronic devices

Solid-State Reaction Synthesis of a InSe/CuInSe₂ Lateral p–n Heterojunction and Application in High Performance Optoelectronic Devices

Graphene-like layered semiconductors are a new class of materials for next generation electronic and optoelectronic devices due to their unique electrical and optical properties. A p–n junction is an elementary building block for electronics and optoelectronics devices. Here, we demonstrate the fabrication of a lateral p–n heterojunction diode of a thin-film InSe/CuInSe₂ nanosheet by simple solid-state reaction. We discover that InSe nanosheets can be easily transformed into CuInSe₂ thin film by reacting with elemental copper at a temperature of 300 °C. Photodetectors and photovoltaic devices based on this lateral heterojunction p–n diode show a large photoresponsivity of 4.2 A W^–1 and a relatively high light-power conversion efficiency of 3.5%, respectively. This work is a giant step forward in practical applications of two-dimensional materials for next generation optoelectronic devices

Sensitive Electronic-Skin Strain Sensor Array Based on the Patterned Two-Dimensional α‑In₂Se₃

Two-dimensional (2D) layered semiconductors have emerged as a highly attractive class of materials for flexible and wearable strain sensor-centric devices such as electronic-skin (e-skin). This is primarily due to their dimensionality, excellent mechanical flexibility, and unique electronic properties. However, the lack of effective and low-cost methods for wafer-scale fabrication of these materials for strain sensor arrays limits their potential for such applications. Here, we report growth of large-scale 2D In₂Se₃ nanosheets by templated chemical vapor deposition (CVD) method, using In₂O₃ and Se powders as precursors. The strain sensors fabricated from the as-grown 2D In₂Se₃ films show 2 orders of magnitude higher sensitivity (gauge factor ∼237 in −0.39% to 0.39% uniaxial strain range along the device channel length) than what has been demonstrated from conventional metal-based (gauge factor: ∼1–5) and graphene-based strain sensors (gauge factor: ∼2–4) in a similar uniaxial strain range. The integrated strain sensor array, fabricated from the template-grown 2D In₂Se₃ films, exhibits a high spatial resolution of ∼500 μm in strain distribution. Our results demonstrate the applicability and highly attractive properties of 2D layered semiconductors in e-skins for robotics and human body motion monitoring