A negative capacitance field-effect transistor (NCFET) built with hafnium-based oxide is one of the most promising candidates for low power-density devices due to the extremely steep subthreshold swing (SS) and high on-state current induced by incorporating the ferroelectric material in the gate stack. Here, we demonstrated a two-dimensional (2D) back-gate NCFET with the integration of ferroelectric HfZrOx in the gate stack and few-layer MoS2 as the channel. Instead of using the conventional TiN capping metal to form ferroelectricity in HfZrOx, the NCFET was fabricated on a thickness-optimized Al2O3/indium tin oxide (ITO)/HfZrOx/ITO/SiO2/Si stack, in which the two ITO layers sandwiching the HfZrOx film acted as the control back gate and ferroelectric gate, respectively. The thickness of each layer in the stack was engineered for distinguishable optical identification of the exfoliated 2D flakes on the surface. The NCFET exhibited small off-state current and steep switching behavior with minimum SS as low as 47 mV/dec. Such a steep-slope transistor is compatible with the standard CMOS fabrication process and is very attractive for 2D logic and sensor applications and future energy-efficient nanoelectronic devices with scaling power supply.

This review briefly describes the development of synthetic topological insulator materials in the application of advanced electronic devices. As a new class of quantum matter, topological insulators with insulating bulk and conducting surface states have attracted attention in more and more research fields other than condensed matter physics due to their intrinsic physical properties, which provides an excellent basis for novel nanoelectronic, optoelectronic, and spintronic device applications. In comparison to the mechanically exfoliated samples, the newly emerging topological insulator nanostructures prepared with various synthetical approaches are more intriguing because the conduction contribution of the surface states can be significantly enhanced due to the larger surface-to-volume ratio, better manifesting the unique properties of the gapless surface states. So far, these synthetic topological insulator nanostructures have been implemented in different electrically accessible device platforms via electrical, magnetic and optical characterizations for material investigations and device applications, which will be introduced in this review.

With the continuous scaling down of devices, traditional one-transistor one-capacitor dynamic random access memory (1T-1C DRAM) has encountered great challenges originated from the large-volume capacitor and high leakage current. A semi-floating gate transistor has been proposed as a capacitor-less memory with ultrafast speed and silicon-compatible technology. In this work, a U-shaped semi-floating gate memory with strain technology has been demonstrated through TCAD simulation. Ultra-high operation speed on a timescale of 5 ns at low operation voltages (≤ 2.0 V) has been obtained. And the tensile stress induced in its channel region by using contact etch stop layer (Si3N4 capper layer) was found to significantly improve the drain current by 12.07%. Furthermore, this device demonstrated a favorable retention performance with a retention time over 1 s, and its immunity to disturbance from bit-line has also been investigated that could maintain data under the continuous worst writing disturbance operation over 10 ms.

Pipeline leakage causes enormous safety and economic concerns; therefore, sensors which are high-performance and durable are in high demand for improving monitoring accuracy and for avoiding economic loss. In this work, mica-based flexible PZT sensors showed high sensitivity, with 140 mV N−1 and 467 mV N−1 for the output voltage, with regard to the tapping and bending modes, respectively. They can monitor airflow in normal conditions with high sensitivity and a linearity of 424 mV MPa−1 and 0.99, respectively. In the event of a pipeline leak, the mica-based sensors exhibited a rapid response time as short as 0.578 s. Furthermore, they generated distinct voltage levels at different distances from the leakage point, thus providing valuable information for accurately locating the source of the leakage.