Since its invention in the 1960s, one of the most significant evolutions of metal-oxide-semiconductor field effect transistors (MOS-FETs) would be the three dimensionalized version that makes the semiconducting channel vertically wrapped by conformal gate electrodes, also recognized as FinFET. During the past decades, the width of fin (W $${}_{{\rm{fin}}}$$fin ) in FinFETs has shrunk from about 150 nm to a few nanometers. However, W $${}_{{\rm{fin}}}$$fin seems to have been levelling off in recent years, owing to the limitation of lithography precision. Here, we show that by adapting a template-growth method, different types of mono-layered two-dimensional crystals are isolated in a vertical manner. Based on this, FinFETs with one atomic layer fin are obtained, with on/off ratios reaching $$\sim\!\! 10^{7}$$~107 . Our findings push the FinFET to the sub 1 nm fin-width limit, and may shed light on the next generation nanoelectronics for higher integration and lower power consumption.

The quantum Hall effect can be substantially affected by interfacial coupling between the host two-dimensional electron gases and the substrate, and has been predicted to give rise to exotic topological states. Yet the understanding of the underlying physics and the controllable engineering of this interaction remains challenging. Here we demonstrate the observation of an unusual quantum Hall effect, which differs markedly from that of the known picture, in graphene samples in contact with an antiferromagnetic insulator CrOCl equipped with dual gates. Two distinct quantum Hall phases are developed, with the Landau levels in monolayer graphene remaining intact at the conventional phase, but largely distorted for the interfacial-coupling phase. The latter quantum Hall phase is even present close to the absence of a magnetic field, with the consequential Landau quantization following a parabolic relation between the displacement field and the magnetic field. This characteristic prevails up to 100 K in a wide effective doping range from 0 to 10¹³ cm⁻².

A solid with larger sound speeds usually exhibits higher lattice thermal conductivity. Here, we report an exception that CuP₂ has a quite large mean sound speed of 4155 m s⁻¹, comparable to GaAs, but single crystals show very low lattice thermal conductivity of about 4 W m⁻¹ K⁻¹ at room temperature, one order of magnitude smaller than GaAs. To understand such a puzzling thermal transport behavior, we have thoroughly investigated the atomic structures and lattice dynamics by combining neutron scattering techniques with first-principles simulations. This compound crystallizes in a layered structure where Cu atoms forming dimers are sandwiched in between P atomic networks. In this work, we reveal that Cu atomic dimers vibrate as a rattling mode with frequency around 11 meV, which is manifested to be remarkably anharmonic and strongly scatters acoustic phonons to achieve the low lattice thermal conductivity.

Thermoelectric (TE) properties of monolayered α-In₂Se₃ are investigated using the first-principles calculations based on the density functional theory and Boltzmann transport theory. The results show that monolayered α-In₂Se₃ is a great candidate for high-performance thermoelectric materials with the power factor PF and the figure of merit ZT as high as 0.02 W/mK² and 2.18 at room temperature, respectively. We attribute such great TE performance to the large electrical conductivity and low lattice thermal conductivity, which originate from unique band structures of group III chalcogenides and anharmonic scattering. Furthermore, we prove that the quantum confinement effect can realize up to an order of magnitude enhancement in the PF. Our findings may open up new possibilities for two-dimensional thermoelectric materials in practical applications.

Recently, the emergent two-dimensional (2D) ferroelectric materials have provided new possibilities for the miniaturization of ferroelectric systems and the integration of novel 2D nano-electronic devices. In addition to the intrinsic ferroelectrics exfoliated from bulk, 2D heterostructures hybridized from electrically non-polarized van der Waals (vdW) materials have also been proven to be a promising platform for the construction of ferroelectricity. Here, we report 30° twisted bilayer–graphene (TBLG) incommensurate moiré superlattice encapsulated by hexagonal boron nitride (h-BN), in which robust hysteretic resistance was detected at the top interface between h-BN and the TBLG from room temperature down to 40 $\mathrm{mK}$. The hysteretic phenomenon can be understood by the extra carrier induced by the interfacial 2D ferroelectric polarization, which is estimated to be around $0.7 \mathrm{pC}/\mathrm{m}$. Our work of interfacial ferroelectric heterostructure achieved by a TBLG/h-BN hybrid system expands the 2D ferroelectric families and opens more possibilities for future coupling the ferroelectricity with rich electronic and optical properties in vdW twistronic devices.

Field effect transistors based on few-layered van der Waals transition metal halide (TMH) Nb₃Cl₈ are studied in this work. Few-layered Nb₃Cl₈ exhibits typical N-type semiconducting behavior controlled by a Si gate, with the electrical signal enhancing as the thickness increases from 4.21 nm to 16.7 nm. Moreover, we find that the tunability of few-layered Nb₃Cl₈ FETs’ electrical transport properties can be significantly augmented through the use of an ionic liquid gate (or electrical double layer, EDL). This enhancement leads to a substantial increase in the on–off ratio by approximately a factor of ${10}^2$, with the transfer curve modulated into a bipolar fashion. The emergence of such bipolar tunable characteristics in Nb₃Cl₈ FETs serves to enrich the electronic properties within the transition metal halide family, positioning Nb₃Cl₈ as a promising candidate for diverse applications spanning transistors, logic circuits, neuromorphic computing and spintronics.