Electrically Tunable Energy Bandgap in Dual-Gated Ultra-Thin Black Phosphorus Field Effect Transistors

The energy bandgap is an intrinsic character of semiconductors, which largely determines their properties. The ability to continuously and reversibly tune the bandgap of a single device during real time operation is of great importance not only to device physics but also to technological applications. Here we demonstrate a widely tunable bandgap of few-layer black phosphorus （BP） by the application of vertical electric field in dual-gated BP field-effect transistors. A total bandgap reduction of 124 meV is observed when the electrical displacement field is increased from 0.10 V/nm to 0.83 V/nm. Our results suggest appealing potential for few-layer BP as a tunable bandgap material in infrared optoelectronies, thermoelectric power generation and thermal imaging.

Charge transport and quantum confinement in MoS2 dual-gated transistors

Semiconductive two dimensional(2D)materials have attracted significant research attention due to their rich band structures and promising potential for next-generation electrical devices.In this work,we investigate the MoS2 field-effect transistors(FETs)with a dual-gated(DG)architecture,which consists of symmetrical thickness for back gate(BG)and top gate(TG)dielectric.The thickness-dependent charge transport in our DG-MoS2 device is revealed by a four-terminal electrical measurement which excludes the contact influence,and the TCAD simulation is also applied to explain the experimental data.Our results indicate that the impact of quantum confinement effect plays an important role in the charge transport in the MoS2 channel,as it confines charge carriers in the center of the channel,which reduces the scattering and boosts the mobility compared to the single gating case.Furthermore,temperature-dependent transfer curves reveal that multi-layer MoS2 DG-FET is in the phonon-limited transport regime,while single layer MoS2 shows typical Coulomb impurity limited regime.

Concise Modeling of Amorphous Dual-Gate In-Ga-Zn-O Thin-Film Transistors for Integrated Circuit Designs

An analytical model for current-voltage behavior of amorphous In-Ga-Zn-O thin-film transistors（a-IGZO TFTs）with dual-gate structures is developed.The unified expressions for synchronous and asynchronous operating modes are derived on the basis of channel charges,which are controlled by gate voltage.It is proven that the threshold voltage of asynchronous dual-gate IGZO TFTs is adjusted in proportion to the ratio of top insulating capacitance to the bottom insulating capacitance（C_（TI）/C_（BI））.Incorporating the proposed model with Verilog-A,a touch-sensing circuit using dual-gate structure is investigated by SPICE simulations.Comparison shows that the touch sensitivity is increased by the dual-gate IGZO TFT structure.

Dual-Gate TFT-LCD抖动算法FRC研究与实现

在TFT-LCD驱动的关键设计技术中,抖动算法FRC(frame rate control)是一种重要的技术。它能够用6 bit source的输出来达到8 bit full color(16.7 M colors)的显示效果,这样可以降低数据传输率以降低功耗,同时可以节省源驱动(Source Driver,SD)芯片的面积。通过分析和实践,提出了针对用于平板电脑的Dual-Gate TFT-LCD屏和翻转方式,需要采用优化的FRC算法提高显示效果。在应用于平板电脑的dual-gate TFT-LCD屏的FRC方案中,分析了传统方案产生周期性竖线的原因,然后提出了改进方案,消除了竖线,提高了显示质量。最后,总结了FRC算法具体需要考虑的因素。

Surface potential-based analytical model for InGaZnO thin-film transistors with independent dual-gates

An analytical drain current model on the basis of the surface potential is proposed for indium-gallium zinc oxide(InGaZnO)thin-film transistors(TFTs)with an independent dual-gate(IDG)structure.For a unified expression of carriers’distribution for the sub-threshold region and the conduction region,the concept of equivalent flat-band voltage and the Lambert W function are introduced to solve the Poisson equation,and to derive the potential distribution of the active layer.In addition,the regional integration approach is used to develop a compact analytical current-voltage model.Although only two fitting parameters are required,a good agreement is obtained between the calculated results by the proposed model and the simulation results by TCAD.The proposed current-voltage model is then implemented by using Verilog-A for SPICE simulations of a dual-gate InGaZnO TFT integrated inverter circuit.

Simulation of optical and electrical synaptic functions in MoS_(2)/α-In_(2)Se_(3) heterojunction memtransistors

Memtransistors combine memristors and field-effect transistors, which can introduce multi-port control and have significant applications for enriching storage methods. In this paper, multilayer α-In2Se3and MoS2were transferred to the substrate by the mechanical exfoliation method, then a heterojunction MoS_(2)/α-In_(2)Se_(3) memtransistor was prepared. Neural synaptic simulations were performed using electrical and optical pulses as input signals. Through measurements, such as excitatory/inhibitory post-synaptic current(EPSC/IPSC), long-term potentiation/depression(LTP/LTD), and paired-pulse facilitation/depression(PPF/PPD), it can be found that the fabricated device could simulate various functions of neural synapses well, and could work as an electronic synapse in artificial neural networks, proposing a possible solution for neuromorphic storage and computation.

M0S2 dual-gate transistors with electrostatically doped contacts

Two-dimensional(2D)transition metal dichalcogenides(TMDs)such as molybdenum disulfide(M0S2)have been intensively investigated because of their exclusive physical properties for advaneed electronics and optoelectronics.In the present work,we study the M0S2 transistor based on a novel tri-gate device architecture,with dual-gate(Dual-G)in the channel and the buried side-gate(Side-G)for the source/drain regi ons.All gates can be in depe ndently con trolled without in terfere nee.For a MoS2 sheet with a thick ness of 3.6 nm,the Schottky barrier(SB)and non-overlapped channel region can be effectively tuned by electrostatically doping the source/drain regions with Side-G.Thus,the extri nsic resista nee can be effectively lowered,and a boost of the ON-state cur re nt can be achieved.Mean while,the cha nn el c ontrol remai ns efficient under the Dual-G mode,with an ON-OFF current ratio of 3 x 107 and subthreshold swing of 83 mV/decade.The corresponding band diagram is also discussed to illustrate the device operati on mechanism.This no vel device structure ope ns up a new way toward fabricati on of high-performance devices based on 2D-TMDs.

Enhancement of rapid lifetime determination for time-resolved fluorescence imaging in forensic examination

An enhancement method of rapid lifetime determination is proposed for time-resolved fluorescence imaging to discriminate substances with approximate fluorescence lifetime in forensic examination. In the method, an image-exclusive-OR treatment with filter threshold adaptively chosen is presented to extract the region of interest from dual-gated fluorescence intensity images, and then the fluorescence lifetime image is reconstructed based on the rapid lifetime determination algorithm. Furthermore, a maximum and minimum threshold filtering is developed to automatically realize visualization enhancement of the lifetime image. In proof experiments, compared with traditional fluorescence intensity imaging and rapid lifetime determination method, the proposed method automatically distinguishes altered and obliterated documents written by two brands of highlighters with the same color and close fluorescence lifetime.

Stacking monolayers at will:A scalable device optimization strategy for two-dimensional semiconductors

In comparison to monolayer(1L),multilayer(ML)two-dimensional(2D)semiconducting transition metal dichalcogenides(TMDs)exhibit more application potential for electronic and optoelectronic devices due to their improved current carrying capability,higher mobility,and broader spectral response.However,the investigation of devices based on wafer-scale ML-TMDs is still restricted by the synthesis of uniform and high-quality ML films.In this work,we propose a strategy of stacking MoS_(2) monolayers via a vacuum transfer method,by which one could obtain wafer-scale high-quality MoS_(2) films with the desired number of layers at will.The optical characteristics of these stacked ML-MoS_(2) films(>2L)indicate a weak interlayer coupling.The stacked MLMoS_(2) phototransistors show improved optoelectrical performances and a broader spectral response(approximately 300-1,000 nm)than that of 1L-MoS_(2).Additionally,the dual-gate ML-MoS_(2) transistors enable enhanced electrostatic control over the stacked ML-MoS_(2) channel,and the 3L and 4L thicknesses exhibit the optimal device performances according to the turning point of the current on/off ratio and the subthreshold swing.