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Ultra-scaled MoS<sub>2</sub> transistors and circuits fabricated without nanolithography
摘要： The future scaling of semiconductor devices can be continued only by the development of novel nanofabrication techniques and atomically thin transistor channels. Here we demonstrate ultra-scaled MoS2 field-effect transistors (FETs) realized by shadow evaporation method which does not require nanofabrication. The method enables large-scale fabrication of MoS2 FETs with fully gated 10-nm long channels. The realized ultra-scaled MoS2 FETs exhibit very small hysteresis of current-voltage characteristics, record high drain currents of ～ 560 A/m, very good drain current saturation for such ultra-short devices, subthreshold swing ～ 120 mV/dec, and drain current on/off ratio ～ 106 in air ambient. The fabricated ultra-scaled MoS2 FETs are also used to realize logic gates in n-type depletion-load technology. The inverters exhibit a voltage gain of ～ 50 at a power supply voltage of only 1.5 V and are capable of in/out signal matching.
关键词： transistor scaling,field-effect transistors,logic gates,MoS2,short-channel effects
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Grain Growth in CdTe Films During CdCl <sub/>2</sub> Treatment: TeCl <sub/>4</sub> Theory
摘要： A diamond metal–semiconductor field-effect transistor (MESFET) with a Pt Schottky gate was fabricated. The MESFET exhibited clear saturation and pinchoff characteristics. The drain current of the MESFET operated at 300 °C was 20 times higher than that at room temperature due to the activation of acceptors. The breakdown voltage was highly dependent on the gate–drain length and reached 1.5 kV at a gate–drain length of 30 μm, which is the highest reported for a diamond FET.
关键词： metal-semiconductor field-effect transistor,Diamond,breakdown voltage
更新于2025-09-23 15:19:57
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Organic thin-film transistors with flame-annealed contacts
摘要： Reducing contact resistance is critical to developing high-performance organic field-effect transistors (OFETs) since it impacts both the device mobility and switching speed. Charge injection and collection has been optimized by applying chemical treatments to the contacts, such as self-assembled monolayers, oxide interlayers, or dopants. Here, we tested how flame annealing the surface of the electrodes impacts the interface and bulk components of the contact resistance, as well as the overall device performance. A butane micro torch was used to flash-anneal the gold electrodes, which allowed gold grains to crystallize into larger domains. We found that, along with the grain size, the surface roughness of the contacts was also increased. Self-assembled monolayer treatment created a lower work function shift on a flame annealed electrode than when deposited on an untreated surface, due to the greater surface roughness. This resulted in a larger interface contact resistance. However, flame annealing also produced an order of magnitude reduction in the density of trap states in the semiconductor layer, which reduced the bulk contact resistance and channel resistance. These competing effects yielded OFETs with similar performance as untreated devices.
关键词： charge injection,contact resistance,organic field-effect transistor
更新于2025-09-23 15:19:57
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Smaller antenna-gate gap for higher sensitivity of GaN/AlGaN HEMT terahertz detectors
摘要： We report an attempt to improve the sensitivity of terahertz detection based on self-mixing in antenna-coupled ?eld-effect transistors by enhancing the ?eld-effect factor and the antenna factor with a reduced gate length and a reduced antenna-gate gap, respectively. An optical noise equivalent power (NEP) of 3:7 pW= ??????Hz at 0.65 THz was achieved in a GaN/AlGaN high-electron-mobility transistor (HEMT) with a gate length of 300 nm and an antenna-gate gap of 200 nm at room temperature. It was found that the antenna factor was inversely proportional to the antenna-gate gap, and the responses upon coherent/incoherent terahertz irradiation were well described by the self-mixing model. To ?ll the NEP gap of 0:1 (cid:2) 1 pW= ??????Hz between room-temperature and cryogenic detectors by HEMT-based detectors at room temperature, impedance match needs to be carefully considered.
关键词： terahertz detection,GaN/AlGaN HEMT,self-mixing,field-effect transistors,antenna-coupled
更新于2025-09-23 15:19:57
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Tungsten Dichalcogenide Nanoflake/InGaZnO Thin-Film Heterojunction for Photodetector, Inverter, and AC Rectifier Circuits
摘要： Heterojunction PN diode and inverter circuits are fabricated and presented, combining two-dimensional WSe2 nanoflake and amorphous InGaZnO (a-IGZO) thin film on a glass substrate. A heterojunction p-WSe2/n-IGZO diode exhibits rectifying characteristics and effectively responds to red light (λ = 620 nm) under a reverse bias. The combination of a heterojunction PN diode and IGZO field effect transistor (FET) leads to a diode-load inverter showing a peak voltage gain of about 12 at a supply voltage of 5 V. The same integration from the PN diode and n-FET displays the capability of visible light detection when a reverse-bias voltage is applied to the PN diode. Furthermore, after oxygen plasma treatment on the PN diode, it shows dramatically enhanced on/off rectification ratio of ≈5 × 105 due to the hole doping effect on the WSe2 nanoflake. Such an improved PN diode leads to an alternating current rectifier circuit as integrated with IGZO FET.
关键词： field-effect transistor (FET),inverter,WSe2,InGaZnO (IGZO),heterojunction PN diode,AC rectifier
更新于2025-09-23 15:19:57
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MoS <sub/>2</sub> Assisted Self-Assembled Poly (3-hexylthiophene) Thin Films at Air/Liquid Interface for High-Performance Field-Effect Transistors under Ambient Condition
摘要： It is a key challenge to achieve long-range ordering in nanoscale morphology of π-conjugated polymers for efficient charge transport in organic electronic devices. The long-range ordering and aggregation in poly (3-hexylthiophene) (P3HT) has been accomplished by introducing two dimensional (2D) Molybdenum disulfide (MoS2) nanosheets in polymer matrix followed by ultrasonication in chloroform. Thin films of synthesized P3HT/MoS2 nanocomposites having various fractions of MoS2 in the P3HT matrix have been fabricated on the air/liquid interface. The UV visible absorption spectroscopy has been employed to investigate the nature of aggregation and exciton bandwidth in the resultant films deposited at the air/liquid interface. Moreover, grazing incidence X-ray diffraction (GIXD) analysis, and atomic force microscopy (AFM), reveal the long-range ordering and highly crystalline thin films with the edge-on orientation of polymer chains over the substrate. Further, the impact of aggregation, morphology, and orientation on macroscopic charge transport performance is elaborately estimated by fabricating organic field-effect transistors (OFETs). The hole mobility as high as 0.160 ± 0.007 cm2V-1s-1, has been achieved for P3HT/MoS2 (1%) nanocomposite under ambient condition.
关键词： organic field-effect transistors,MoS2,π-conjugated polymers,nanocomposites,P3HT,charge transport
更新于2025-09-23 15:19:57
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Imaging Carrier Inhomogeneities in Ambipolar Tellurene Field Effect Transistors
摘要： Developing van der Waals (vdW) homojunction devices requires materials with narrow bandgaps and simultaneously high hole and electron mobilities for bipolar transport, as well as methods to image and study spatial variations in carrier type and associated conductivity with nanometer spatial resolution. Here we demonstrate the general capability of near-field scanning microwave microscopy (SMM) to image and study the local carrier type and associated conductivity in operando by studying ambipolar field effect transistors (FETs) of the 1D vdW material tellurium in 2D form. To quantitatively understand electronic variations across the device, we produce nanometer resolved maps of the local carrier equivalence backgate voltage. We show that the global device conductivity minimum determined from transport measurements does not arise from uniform carrier neutrality, but rather from the continued coexistence of p-type regions at the device edge and n-type regions in the interior of our micron-scale devices. This work both underscores and addresses the need to image and understand spatial variations in the electronic properties of nanoscale devices.
关键词： 2D Materials,Field-Effect Transistor,Microwave,Near-Field Microscopy,Atomic Force Microscope
更新于2025-09-19 17:15:36
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SnSe2 Field-Effect Transistor with High On/Off Ratio and Polarity-Switchable Photoconductivity
摘要： SnSe2 field-effect transistor was fabricated based on exfoliated few-layered SnSe2 flake, and its electrical and photoelectric properties have been investigated in detail. With the help of a drop of de-ionized (DI) water, the SnSe2 FET can achieve an on/off ratio as high as ~ 104 within 1 V bias, which is ever extremely difficult for SnSe2 due to its ultrahigh carrier density (1018/cm3). Moreover, the subthreshold swing and mobility are both improved to ～ 62 mV/decade and ~ 127 cm2 V?1 s?1 at 300 K, which results from the efficient screening by the liquid dielectric gate. Interestingly, the SnSe2 FET exhibits a gate bias-dependent photoconductivity, in which a competition between the carrier concentration and the mobility under illumination plays a key role in determining the polarity of photoconductivity.
关键词： Photoconductivity,SnSe2,Field-effect transistor,On/off ratio
更新于2025-09-19 17:15:36
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van der Waals Epitaxial Growth of Atomically Thin 2D Metals on Dangling-Bond-Free WSe <sub/>2</sub> and WS <sub/>2</sub>
摘要： 2D metals have attracted considerable recent attention for their special physical properties, such as charge density waves, magnetism, and superconductivity. However, despite some recent efforts, the synthesis of ultrathin 2D metals nanosheets down to monolayer thickness remains a significant challenge. Herein, by using atomically flat 2D WSe2 or WS2 as the growth substrate, the synthesis of atomically thin 2D metallic MTe2 (M = V, Nb, Ta) single crystals with the thickness down to the monolayer regime and the creation of atomically thin MTe2/WSe2 (WS2) vertical heterojunctions is reported. Comparison with the growth on the SiO2/Si substrate under the same conditions reveals that the utilization of the dangling-bond-free WSe2 or WS2 as the van der Waals epitaxy substrates is crucial for the successful realization of atomically thin MTe2 (M = V, Nb, Ta) nanosheets. It is further shown that the epitaxial grown 2D metals can function as van der Waals contacts for 2D semiconductors with little interface damage and improved electronic performance. This study defines a robust van der Waals epitaxy pathway to ultrathin 2D metals, which is essential for fundamental studies and potential technological applications of this new class of materials at the 2D limit.
关键词： van der Waals epitaxy,field-effect transistors,2D materials,chemical vapor deposition,transition metal dichalcogenides
更新于2025-09-19 17:15:36
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Progress of power field effect transistor based on ultra-wide bandgap Ga <sub/>2</sub> O <sub/>3</sub> semiconductor material
摘要： As a promising ultra-wide bandgap semiconductor, gallium oxide (Ga2O3) has attracted increasing attention in recent years. The high theoretical breakdown electrical field (8 MV/cm), ultra-wide bandgap (~ 4.8 eV) and large Baliga’s figure of merit (BFOM) of Ga2O3 make it a potential candidate material for next generation high-power electronics, including diode and field effect transistor (FET). In this paper, we introduce the basic physical properties of Ga2O3 single crystal, and review the recent research process of Ga2O3 based field effect transistors. Furthermore, various structures of FETs have been summarized and compared, and the potential of Ga2O3 is preliminary revealed. Finally, the prospect of the Ga2O3 based FET for power electronics application is analyzed.
关键词： ultra-wide bandgap semiconductor,field effect transistor (FET),power device,gallium oxide (Ga2O3)
更新于2025-09-19 17:15:36