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Transconductance Amplification in Dirac-Source Field-Effect Transistors Enabled by Graphene/Nanotube Hereojunctions
摘要： Steep-slope devices are predicted to provide excellent quality for analog integrated circuit applications due to their high transconductance efficiency (gm/Ids) breaking the metal-oxide-semiconductor field-effect transistor limit (38.5 V?1). The potential advantage of a Dirac-source FET (DSFET) as an analog transistor is explored based on a graphene/carbon nanotube (CNT) heterojunction. A high gm/Ids beyond 38.5 V?1 over four decades of current is experimentally demonstrated in an individual CNT-based DSFET, reaching a peak value of 66 V?1, which is a new record for all reported transistors. Importantly, this high gm/Ids extends beyond the subthreshold region and leads to transconductance amplification in the overthreshold region. The best peak transconductance at a low bias of ?0.1 V exceeds 20 μS per tube, which has approximately threefold improvement over that of a normal CNT FET with a shorter gate length. Outperforming other advanced devices, the extended high transconductance efficiency greatly promotes DSFET competitiveness in the high-precision analog field.
关键词： carbon nanotubes,heterojunctions,Dirac sources,graphene,field-effect transistors
更新于2025-09-23 15:21:01
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Wafer Scale Graphene Field Effect Transistors on Thin Thermal Oxide
摘要： In this study, we present the feasibility to fabricate back-gated graphene field-effect transistors (GFETs) on 10 nm thermal SiO2 substrate. Here, we compare the mobility of graphene devices at different locations of the transferred CVD graphene. We observed that there is a n-type doping of the graphene devices with Dirac points within ± 0.5 V from an ideal value of 0 V. The downscaling of the back-gate dielectric thickness reduces the operating voltage range, commonly required for low power electronics, and the devices are stable during operation in air under ambient conditions. The extracted contact resistance is comparable to the earlier reports found in literature and this provides a feasibility to fabricate low power futuristic graphene based nanoelectronics.
关键词： CVD graphene,n-type doping,thermal SiO2,mobility,Dirac points,low power electronics,field-effect transistors,graphene,contact resistance
更新于2025-09-23 15:21:01
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<i>(Invited) The Scaling-Down and Performance Optimization of InAs Nanowire Field Effect Transistors</i>
摘要： Due to their fascinating properties, InAs nanowires have drawn great attention for the channel material in future transistors. Scaling-down has been an effective way to improve the performance of transistors continuously for decades. Here, we review our recent progresses on InAs nanowire field effect transistors (FETs) when they are scaled down. Our group investigates the electrical characteristics of InAs nanowire thinner than 10 nm. Both the size-effect and the contact properties of ultrathin nanowires are explored. Moreover, the effects of InAs crystal phase and orientation are studied for further optimizing the device performance. In addition, FETs with partial gate are studied to suppress the BTBT-induced off-current. Furthermore, to improve the electrostatics control of the gate, our group develops a method to fabricate vertical GAA FETs with all-metal electrodes based on self-catalyzed grown InAs nanowire arrays.
关键词： orientation,crystal phase,performance optimization,field effect transistors,partial gate,vertical GAA FETs,InAs nanowires,scaling-down
更新于2025-09-23 15:21:01
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Hydrogen Sensing Characteristics of AlGaInP/InGaAs Complementary Co-Integrated Pseudomorphic Doping-Channel Field-Effect Transistors
摘要： In this article, the hydrogen sensing device and logic characteristics of the Al0.25Ga0.25In0.5P/In0.1Ga0.9As complementary co-integrated pseudomorphic doping-channel ?eld-effect transistors are demonstrated. Due to the existence of a relatively large conduction (valence) band discontinuity at Al0.25Ga0.25In0.5P/In0.1Ga0.9As heterojunction and the employment of a small energy-gap In0.1Ga0.9As channel layer, it could provide a high gate barrier height to avoid electrons (holes) injection form channel into gate region in the studied n-channel (p-channel) device. With respect to the n-channel (p-channel) transistor under hydrogen ambient, hydrogen molecules are adsorbed and dissociated on the Pd catalytic metal surface, followed by rapid diffusion of hydrogen atoms into the MS interface where the dipoles are formed to lower (elevate) the gate barrier height and enhance (decrease) the drain current. In the n-channel (p-channel) device, the threshold voltages at drain current of 0.1 mA/mm are of 0.67 (0.05) and 0.38 (?0.26) V in air and at hydrogen concentration of 9800 ppm, respectively. As hydrogen is detected, the characteristics of inverters shift left obviously, and the VOH and VIH values are decreased.
关键词： field-effect transistors,hydrogen sensing,AlGaInP/InGaAs,logic characteristics
更新于2025-09-23 15:21:01
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Recent Advances in Isoindigo-Inspired Organic Semiconductors
摘要： Over the past decade, isoindigo has become a widely used electron-deficient subunit in donor-acceptor organic semiconductors, and these isoindigo-based materials have been widely used in both organic photovoltaic (OPV) devices and organic field effect transistors (OFETs). Shortly after the development of isoindigo-based semiconductors, researchers began to modify the isoindigo structure in order to change the optoelectronic properties of the resulting materials. This led to the development of many new isoindigo-inspired compounds; since 2012, the Kelly Research Group has synthesized a number of these isoindigo analogues and produced a variety of new donor-acceptor semiconductors. In this Personal Account, recent progress in the field is reviewed. We describe how the field has evolved from relatively simple donor-acceptor small molecules to structurally complex, highly planarized polymer systems. The relevance of these materials in OPV and OFET applications is highlighted, with particular emphasis on structure-property relationships.
关键词： isoindigo,organic field effect transistors,organic materials,organic photovoltaics,conjugated polymers
更新于2025-09-23 15:21:01
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Chemical and Biomolecule Sensing with Organic Field-Effect Transistors
摘要： The strong and controllable chemical sensitivity of organic semiconductors (OSCs) and the amplification capability of transistors in circuits make use of OSC-based field-effect transistors compelling for chemical sensors. Analytes detected and assayed range from few-atom gas-phase molecules that may have adverse health and security implications to biomacromolecules (proteins, nucleic acids) that may be markers for physiological processes and medical conditions. This review highlights recent progress in organic field-effect transistor (OFET) chemical sensors, emphasizing advances from the past 5 years and including aspects of OSC morphology and the role of adjacent dielectrics. Design elements of the OSCs and various formats for the devices are illustrated and evaluated. Challenges associated with the present state of the art and future opportunities are also discussed.
关键词： organic field-effect transistors,organic semiconductors,dielectrics,biomacromolecules,chemical sensors
更新于2025-09-23 15:21:01
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Liquid Phase Exfoliated Indium Selenide Based Highly Sensitive Photodetectors
摘要： Layered semiconductors of the IIIA–VIA group have attracted considerable attention in (opto)electronic applications thanks to their atomically thin structures and their thickness-dependent optical and electronic properties, which promise ultrafast response and high sensitivity. In particular, 2D indium selenide (InSe) has emerged as a promising candidate for the realization of thin-film field effect transistors and phototransistors due to its high intrinsic mobility (>102 cm2 V?1 s?1) and the direct optical transitions in an energy range suitable for visible and near-infrared light detection. A key requirement for the exploitation of large-scale (opto)electronic applications relies on the development of low-cost and industrially relevant 2D material production processes, such as liquid phase exfoliation, combined with the availability of high-throughput device fabrication methods. Here, a β polymorph of indium selenide (β-InSe) is exfoliated in isopropanol and spray-coated InSe-based photodetectors are demonstrated, exhibiting high responsivity to visible light (maximum value of 274 A W?1 under blue excitation 455 nm) and fast response time (15 ms). The devices show a gate-dependent conduction with an n-channel transistor behavior. Overall, this study establishes that liquid phase exfoliated β-InSe is a valid candidate for printed high-performance photodetectors, which is critical for the development of industrial-scale 2D material-based optoelectronic devices.
关键词： photodetectors,2D semiconductors,indium selenide,field effect transistors,liquid phase exfoliation,spray coating,solution processed
更新于2025-09-23 15:19:57
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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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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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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