Junhao Chu

Bio: Junhao Chu is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Thin film & Ferroelectricity. The author has an hindex of 37, co-authored 322 publications receiving 5256 citations. Previous affiliations of Junhao Chu include East China Normal University & ShanghaiTech University.

Ultrasensitive and Broadband MoS2 Photodetector Driven by Ferroelectrics

Abstract: A few-layer MoS2 photodetector driven by poly(vinylidene fluoride-trifluoroethylene) ferroelectrics is achieved. The detectivity and responsitivity are up to 2.2 × 10(12) Jones and 2570 A W(-1), respectively, at 635 nm with ZERO gate bias. E(g) of MoS2 is tuned by the ultrahigh electrostatic field from the ferroelectric polarization. The photoresponse wavelengths of the photodetector are extended into the near-infrared (0.85-1.55 μm).

High-Performance Photovoltaic Detector Based on MoTe2 /MoS2 Van der Waals Heterostructure.

Abstract: Van der Waals heterostructures based on 2D layered materials have received wide attention for their multiple applications in optoelectronic devices, such as solar cells, light-emitting devices, and photodiodes. In this work, high-performance photovoltaic photodetectors based on MoTe2 /MoS2 vertical heterojunctions are demonstrated by exfoliating-restacking approach. The fundamental electric properties and band structures of the junction are revealed and analyzed. It is shown that this kind of photodetectors can operate under zero bias with high on/off ratio (>105 ) and ultralow dark current (≈3 pA). Moreover, a fast response time of 60 µs and high photoresponsivity of 46 mA W-1 are also attained at room temperature. The junctions based on 2D materials are expected to constitute the ultimate functional elements of nanoscale electronic and optoelectronic applications.

Highly sensitive visible to infrared MoTe2 photodetectors enhanced by the photogating effect.

Abstract: Two-dimensional materials are promising candidates for electronic and optoelectronic applications. MoTe2 has an appropriate bandgap for both visible and infrared light photodetection. Here we fabricate a high-performance photodetector based on few-layer MoTe2. Raman spectral properties have been studied for different thicknesses of MoTe2. The photodetector based on few-layer MoTe2 exhibits broad spectral range photodetection (0.6-1.55 μm) and a stable and fast photoresponse. The detectivity is calculated to be 3.1 × 10(9) cm Hz(1/2) W(-1) for 637 nm light and 1.3 × 10(9) cm Hz(1/2) W(-1) for 1060 nm light at a backgate voltage of 10 V. The mechanisms of photocurrent generation have been analyzed in detail, and it is considered that a photogating effect plays an important role in photodetection. The appreciable performance and detection over a broad spectral range make it a promising material for high-performance photodetectors.

Programmable transition metal dichalcogenide homojunctions controlled by nonvolatile ferroelectric domains

Abstract: Semiconductor devices based on two-dimensional (2D) transition metal dichalcogenides could help overcome the scaling limits of silicon complementary metal–oxide–semiconductor (CMOS) technology. However, the development of atomically thin devices requires approaches to control the carrier type in 2D semiconductors. Here, we show that a scanning probe can be used to control the polarization of ferroelectric polymers deposited on 2D transition metal dichalcogenides in order to define carrier injection and achieve p-type and n-type doping. The approach allows lateral p–n, n–p, n–n and p–p homojunctions to be arbitrarily formed and altered. Molybdenum ditelluride (MoTe2) p–n homojunction devices constructed using this method exhibit high current rectification ratios of 103 and good optoelectronic properties (responsivity of 1.5 A W−1). Unconventional nonvolatile memory devices are also built, such as an electrical writing and optical reading memory device, without the restrictions of physical source, drain or gate electrodes, and a quasi-nonvolatile memory with a refresh time of 100 s and a write/erase speed of 10 µs. By using a scanning probe to control the polarization of ferroelectric polymers deposited on the surface of two-dimensional transition metal dichalcogenides, optoelectronic and unconventional memory devices can be created based on lateral p–n junctions.

Recent Progress in Multiferroic Magnetoelectric Composites: from Bulk to Thin Films

Abstract: Multiferroic magnetoelectric composite systems such as ferromagnetic-ferroelectric heterostructures have recently attracted an ever-increasing interest and provoked a great number of research activities, driven by profound physics from coupling between ferroelectric and magnetic orders, as well as potential applications in novel multifunctional devices, such as sensors, transducers, memories, and spintronics. In this Review, we try to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.

Caloric materials near ferroic phase transitions

Abstract: A magnetically, electrically or mechanically responsive material can undergo significant thermal changes near a ferroic phase transition when its order parameter is modified by the conjugate applied field. The resulting magnetocaloric, electrocaloric and mechanocaloric (elastocaloric or barocaloric) effects are compared here in terms of history, experimental method, performance and prospective cooling applications.

Introduction To Electrodynamics

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Molecular Design of Benzodithiophene-Based Organic Photovoltaic Materials.

Abstract: Advances in the design and application of highly efficient conjugated polymers and small molecules over the past years have enabled the rapid progress in the development of organic photovoltaic (OPV) technology as a promising alternative to conventional solar cells. Among the numerous OPV materials, benzodithiophene (BDT)-based polymers and small molecules have come to the fore in achieving outstanding power conversion efficiency (PCE) and breaking 10% efficiency barrier in the single junction OPV devices. Remarkably, the OPV device featured by BDT-based polymer has recently demonstrated an impressive PCE of 11.21%, indicating the great potential of this class of materials in commercial photovoltaic applications. In this review, we offered an overview of the organic photovoltaic materials based on BDT from the aspects of backbones, functional groups, alkyl chains, and device performance, trying to provide a guideline about the structure-performance relationship. We believe more exciting BDT-based photovol...