Van der Waals metal gate to two-dimensional semiconductors enables low-power electronic devices.

Deep ultraviolet (DUV) photodetection usually relies on wide-bandgap semiconductors, which however face challenges in material growth and doping processes. In this work, we proposed and validated a photodetection scheme based on tunneling barrier modulation, achieving highly sensitive DUV photodetection. Using a two-dimensional van der Waals heterostructure, the device integrates MoS₂ as the transporting layer for its high carrier mobility and low dark current, few-layered graphene (FLG) as the photon absorption layer, and hexagonal boron nitride (hBN) as the dielectric barrier. The device exhibits an photoresponsivity of 4.4 × 10⁶A·W^-1 and specific detectivity of 1.4 × 10¹⁷ \({{{\rm{cm}}}}\cdot {{{{\rm{H}}}}{{{\rm{z}}}}}^{-1/2}\cdot {{{{\rm{W}}}}}^{-1}\) for 250 nm DUV light, with a rejection ratio R₂₅₀/R₄₅₀ exceeding 10⁶ for visible light. Unlike conventional photodetectors, the cutoff wavelength is determined by the tunneling barrier rather than the material bandgap. Additionally, this photodetection scheme has been extended to a wide range of materials, utilizing different charge transporting layer (e.g., MoS₂, ReS₂), barrier layer (e.g., hBN, Al₂O₃), and photon absorption materials (e.g., FLG, PdSe₂, Au, Pd), showcasing its broad adaptability and potential for extensive application. Furthermore, the device has been successfully employed as a power meter for weak UV radiation (0.1 μW·cm^-2) and for measuring solar UV irradiance with results matching the meteorological agency’s weather reports. Overall, this work introduces an effective approach for developing high-performance DUV photodetectors, highlighting significant potential for applications in the optoelectronic market.

Modern electronics demand transistors with extremely high performance and energy efficiency. Charge-based transistors with conventional semiconductors experience substantial heat dissipation because of carrier scattering. Here, we demonstrate low-loss topological phase change transistors (TPCTs) based on tellurium, a Weyl semiconductor. By modulating the energy separation between the Fermi level and the Weyl point of tellurium through electrostatic gate modulation, the device exhibits topological phase change between Weyl (Chern number ≠ 0) and conventional (Chern number = 0) semiconductors. In the Weyl ON state, the device has low-loss transport characteristics due to the global topology of gauge fields against external perturbations; the OFF state exhibits trivial charge transport in the conventional phase by moving the Fermi level into the bandgap. The TPCTs show a high ON/OFF ratio (10⁸) at low operation voltage (≤2 volts) and high ON-state conductance (39 mS/μm). Our studies provide alternative strategies for realizing ultralow power electronics.

In this study, the effects of doping with different contents of the rare-earth element yttrium (Y) on the electrical performance of indium zinc oxide (IZO) and bilayer IZO/IYZO thin-film transistors (TFTs) were investigated. Through a rational design, the bilayer IZO/IYZO TFT exhibits the best performance with a Vth of 0.2 V and μFE of 32.6 cm2/V s. X-ray photoelectron spectroscopy band structure analysis demonstrated that, in the IZO/IYZO TFT, a 6-nm highly conductive ultrathin IZO provided free electrons and electron transfer from the IZO layer to the IYZO layer with the formation of band bending, thus increased the carrier mobility of devices. In addition, the 20-nm-thick IYZO layer controlled Ne and Vth by forming a potential barrier (0.38 eV), thereby increasing stability. Moreover, the experimental characterization revealed that Y doping can reduce the carrier concentration, oxygen vacancies, surface defects, and other trap densities of devices. Therefore, the IZO/IYZO TFT demonstrated the best stability with small Vth shifts of −0.9, 0.8, −1.1, and 1.0 V under negative gate bias stress, positive gate bias stress, negative gate bias light illumination stress, and positive gate bias light illumination stress measurements. Overall, the designed IZO/IYZO TFTs open effective pathways for achieving high-performance oxide TFTs.