Synthesis of Two-Dimensional MoO2 Nanoplates with Large Linear Magnetoresistance and Nonlinear Hall Effect.

Two-dimensional (2D) materials with large linear magnetoresistance (LMR) are very interesting owing to their potential application in magnetic storage or sensor devices. Here, we report the synthesis of 2D MoO2 nanoplates grown by a chemical vapor deposition (CVD) method and observe large LMR and nonlinear Hall behavior in MoO2 nanoplates. As-obtained MoO2 nanoplates exhibit rhombic shapes and high crystallinity. Electrical studies indicate that MoO2 nanoplates feature a metallic nature with an excellent conductivity of up to 3.7 × 107 S m-1 at 2.5 K. MoO2 nanoplates display a large LMR of up to 455% at 3 K and -9 T. A thickness-dependent LMR analysis suggests that LMR values increase upon increasing the thickness of nanoplates. Besides, nonlinearity has been found in the magnetic-field-dependent Hall resistance, which decreases with increasing temperatures. Our studies highlight that MoO2 nanoplates are promising materials for fundamental studies and potential applications in magnetic storage devices.

Coupled Ferroelectric-Photonic Memory in a Retinomorphic Hardware for In-Sensor Computing.

The development of all-in-one devices for artificial visual systems offers an attractive solution in terms of energy efficiency and real-time processing speed. In recent years, the proliferation of smart sensors in the growth of Internet-of-Things (IoT) has led to the increasing importance of in-sensor computing technology, which places computational power at the edge of the data-flow architecture. In this study, a prototype visual sensor inspired by the human retina is proposed, which integrates ferroelectricity and photosensitivity in two-dimensional (2D) α-In2Se3 material. This device mimics the functions of photoreceptors and amacrine cells in the retina, performing optical reception and memory computation functions through the use of electrical switching polarization in the channel. The gate-tunable linearity of excitatory and inhibitory functions in photon-induced short-term plasticity enables to encode and classify 12 000 images in the Mixed National Institute of Standards and Technology (MNIST) dataset with remarkable accuracy, achieving ≈94%. Additionally, in-sensor convolution image processing through a network of phototransistors, with five convolutional kernels electrically pre-programmed into the transistors is demonstrated. The convoluted photocurrent matrices undergo straightforward arithmetic calculations to produce edge and feature-enhanced scenarios. The findings demonstrate the potential of ferroelectric α-In2Se3 for highly compact and efficient retinomorphic hardware implementation, regardless of ambipolar transport in the channel.

Controllable Oxidation of ZrS2 to Prepare High-κ, Single-Crystal m-ZrO2 for 2D Electronics.

High-κ materials that exhibit large permittivity and band gaps are needed as gate dielectrics to enhance capacitance and prevent leakage current in downsized technology nodes. Among these, monoclinic ZrO2 (m-ZrO2 ) shows good potential because of its inertness and high-κ with respect to SiO2 , but a method to produce ultrathin single crystal is lacking. Here, the controllable preparation of ultrathin m-ZrO2 single crystals via the in situ thermal oxidation of ZrS2 is achieved. As-grown m-ZrO2 presents an equivalent oxide thickness of ≈0.29 nm, a high dielectric constant of ≈19, and a breakdown voltage (EBD ) of ≈7.22 MV cm-1 . MoS2 field effect transistor (FET) by using m-ZrO2 as a dielectric layer shows comparable mobility to that using SiO2 dielectric. The ultraclean interface of m-ZrO2 /MoS2 and high crystalline quality of m-ZrO2 lead to negligible hysteresis in transfer curves. Single crystal m-ZrO2 dielectric shows potential application in digital complementary metal oxidesemiconductor (CMOS) logic FET.