Search

Two-dimensional (2D) atomic threshold switching field-effect transistors (ATS-FETs), which integrate 2D FET with threshold switching (TS) devices, have garnered attention as part of the subthreshold swing (SS) improvement for next-generation low-power devices. For industrial applications of 2D ATS-FET, it is important to secure the threshold voltage (Vth) modulation technique. Here, Vth engineering is performed by altering the counter electrode (CE) of a TS device, and the electrical performance of the ATS-FET is systematically investigated. The work function difference between the active electrode and CE alters the internal electric field (E-field) formed between these two electrodes. This severely affects the metal ion migration of the active electrode and induces the Vth shift of the ATS-FET. Because the proposed Vth adjusting technique does not affect the channel material, the MoS2 ATS-FET with the proposed technique can shift Vth while maintaining a high on–off ratio of >105 A on average and achieves an ultra-low average SS of ∼10.929 mV/dec. Moreover, the SS variation due to the random interface traps between the channel and gate dielectric is sufficiently suppressed. This study is expected to be a cornerstone for ATS-FET research by offering a compact platform to adjust Vth without deteriorating steep-slope characteristics.

The breakup mechanism of a microbubble in a 2D channel, was studied through visualization experiments. A venturi-shaped nozzle made with a 3D printer in a 2D channel was employed, and the pressure data and visualization images were analyzed. It is compared that he bubble behavior and size distribution according to the change in the rear-end exit angle of the venturi-shaped nozzle. As the exit angle increased, the bubble size decreased. However, it was confirmed that wake flow was formed in the venturi channel with an exit angle above 20°. By analyzing the visualization, we confirmed that the air bubbles interacted with the central flow and split into pieces. To maximize this process, a flare-shaped diffuser was designed and evaluated. The bubble breakup performance of the flared diffuser was better than that of the linear exit angle, in terms of the bubble size. It was a flared diffuser that satisfied the conditions for maximizing the bubble breakup process in a water flow rate of (35 L/min) and an air flow rate (0.1 L/MIN) experiments. Based on the results, it is expected that the limitations of the venturi-shaped microbubble generator can be overcome.

Abstract For next‐generation electronics and optoelectronics, 2D‐layered nanomaterial‐based field effect transistors (FETs) have garnered attention as promising candidates owing to their remarkable properties. However, their subthreshold swings (SS) cannot be lower than 60 mV/decade owing to the limitation of the thermionic carrier injection mechanism, and it remains a major challenge in 2D‐layered nanomaterial‐based transistors. Here, a gate‐connected MoS2 atomic threshold switching FET using a nitrogen‐doped HfO2‐based threshold switching (TS) device is developed. The proposed device achieves an extremely low SS of 11 mV/decade and a high on‐off ratio of ≈106 by maintaining a high on‐state drive current due to the steep switching of the TS device at the gate region. In particular, the proposed device can function as an infrared detectable phototransistor with excellent optical properties. The proposed device is expected to pave the way for the development of future 2D channel‐based electrical and optical transistors.