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Solar-blind deep-ultraviolet photodetectors based on solution-synthesized quasi-2D Te nanosheets
摘要： Solar-blind deep ultraviolet (DUV) photodetectors with high responsivity (R) and fast response speed are crucial for practical applications in astrophysical analysis, environmental pollution monitoring, and communication. Recently, 2D tellurium has emerged as a potential optoelectronic material because of its excellent photoelectric properties. In this study, solar-blind DUV photodetectors are demonstrated based on solution-synthesized and air-stable quasi-2D Te nanosheets (Te NSs). An R of 6.5×104 A/W at 261 nm and an external quantum efficiency (EQE) of higher than 2.26×106% were obtained, which are highest among most other 2D material-based solar-blind DUV photodetectors. Moreover, the photoelectric performance of the quasi-2D Te-based photodetector exhibited good stability even after ambient exposure for 90 days without any encapsulation. These results indicate that quasi-2D Te NSs provide a viable approach for developing solar-blind DUV photodetectors with ultrahigh R and EQE.
关键词： FET,photodetector,solar-blind deep ultraviolet,quasi-2D Te nanosheets
更新于2025-09-19 17:13:59
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Transition from Hopping to Band-like Transport in Weakly-coupled Multilayer MoS2 Field Effect Transistors
摘要： In this article, multilayer MoS2 manufactured from multiple-transfer process of chemical vapor deposition (CVD) grown monolayer MoS2 is studied. Due to the lattice mismatch and larger distance between adjacent MoS2 layers, the interlayer-interaction is weakened and the band structure transition from direct to indirect as well as band-gap shrinkage effect in multilayer is suppressed, as indicated by Raman and photoluminescence (PL) spectra. These structural differences from that of the exfoliated MoS2 make stacked MoS2 layers a better configuration for fabricating high-performance MoS2 FET. Here, back-gate MoS2 field effect transistors (FETs) with different number of layers were fabricated. As the number of layers increases from 1 to 3, the devices’ mobility and on/off ratio show an enhancement from 2 to 62cm2/s·V and 106 to 108, respectively. Metal to insulator transition (MIT) phenomena is also observed in bilayer MoS2 FET. A distributed resistance based model is proposed to study the conductivity of weak-coupled MoS2 layers. Combining the resistance model with temperature dependence characteristics, it is demonstrated that the electron mobility in monolayer MoS2 is limited by hopping transport mechanism, whereas the electron in bilayer can be excited to band-like transport mode due to the immunity of the influence from the charge traps at substrate, which explain the enhancement of mobility and MIT phenomena. This study is universally valid for other two dimensional (2D) materials, paving a way to fabricate high performance nano-electronics for integrated circuits.
关键词： CVD,MoS2,multilayer,metal-to-insulator transition,FET
更新于2025-09-19 17:13:59
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Asymmetric Dual Grating Gate Graphene-based THz detectors
摘要： We report on detection of terahertz radiation by using asymmetric dual-grating gates graphene-based FET. The graphene sheet was sandwiched between two layers of hexagonal Boron Nitride (h-BN) to avoid interaction with the substrate and enhance carrier mobility. Asymmetric dual metal gates were processed on the top of the upper h-BN layer. The devices were excited with terahertz radiation at frequencies of 0.15 and 0.3 THz and a clear photocurrent was observed from 4K up to room temperature.
关键词： FET,detectors,h-BN,terahertz,graphene
更新于2025-09-16 10:30:52
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Solution-processed P3HT:PbS based NIR Photodetector with FET Configuration
摘要： A near-infrared (NIR) solution-processed photodetector based on a mixture of PbS colloidal quantum dots (CQDs) and Poly(3-hexylthiophene) (P3HT) was presented. In a reverse field-effect transistor (FET) device configuration Au(S,D)/P3HT:PbS/PMMA/Al(G), uniform-sized and well-dispersed PbS CQDs were employed as NIR absorbing materials in the active layer. Meanwhile, the poly(methyl methacrylate) (PMMA) dielectric layer could be seen as an encapsulation to enhance the device stability. Herein, High “on/off” current ratio (Ion/Ioff) of 104 was obtained in dark, and the maximum photosensitivity (P) of 947 was gotten under 200 mW/cm2 980 nm illumination. When the irradiance reduced to 0.1 mW/cm2, the responsivity (R) and detectivity (D?) of the NIR photodetector reached 9.4 mA/W and 2.5×1011 Jones, respectively. Therefore, the P3HT:PbS hybrid FET-based NIR photodetector had shown both relatively high electrical and detecting performance, which provided an experimental foundation and method for the next fabrication of medical infrared detectors and sensors.
关键词： PbS colloidal quantum dots (CQDs),Near-infrared (NIR) photodetector,Poly(3-hexylthiophene) (P3HT),Field-effect transistor (FET)
更新于2025-09-16 10:30:52
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[IEEE 2019 Sixteenth International Conference on Wireless and Optical Communication Networks (WOCN) - Bhopal, India (2019.12.19-2019.12.21)] 2019 Sixteenth International Conference on Wireless and Optical Communication Networks (WOCN) - Stub Loaded Semi-Circular Resonator for Filter Applications
摘要： Tunnel FETs (TFETs) have been identified as the most promising steep slope devices for ultralow power logic circuits. In this paper, we demonstrate in-plane InAs/Si TFETs monolithically integrated on Si, using our recently developed template-assisted selective epitaxy approach. These devices represent some of the most scaled TFETs with dimensions of less than 30 nm, combined with excellent aggregate performance with average subthreshold swing (SS), of around 70 mV/decade combined with ION of a few μA/μm for |VDS| = |VGS| = 0.5 V. Here, we will discuss the device fabrication as well as the experimental electrical data. Extensive low temperature characterization and activation energy analysis is used to gain insights into the factors limiting device performance. Combined with the simulation study presented in part 2 of this paper, this will elucidate how traps are ultimately limiting the SS.
关键词： selective epitaxy,tunnel FET (TFET),InAs,Heterojunction device
更新于2025-09-16 10:30:52
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Direct Laser Patterning and Phase Transformation of 2D PdSe <sub/>2</sub> Films for On-Demand Device Fabrication
摘要： Heterophase homojunction formation in atomically thin 2D layers is of great importance for next-generation nanoelectronics and optoelectronics applications. Technologically challenging, controllable transformation between the semiconducting and metallic phases of transition metal chalcogenides is of particular importance. Here, we demonstrate that controlled laser irradiation can be used to directly ablate PdSe2 thin films using high power or trigger the local transformation of PdSe2 into a metallic phase PdSe2?x using lower laser power. Such transformations are possible due to the low decomposition temperature of PdSe2 and a variety of stable phases compared to other 2D transition metal dichalcogenides. Scanning transmission electron microscopy is used to reveal the laser-induced Se-deficient phases of PdSe2 material. The process sensitivity to the laser power allows patterning flexibility for resist-free device fabrication. The laser-patterned devices demonstrate that a laser-induced metallic phase PdSe2?x is stable with increased conductivity by a factor of about 20 compared to PdSe2. These findings contribute to the development of nanoscale devices with homojunctions and scalable methods to achieve structural transformations in 2D materials.
关键词： device fabrication,phase transformation,PdSe2,FET,laser patterning,2D materials,graphene
更新于2025-09-12 10:27:22
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Monolithically Integrated GaN LED/Quasi-Vertical Power U-shaped Trench-gate MOSFET Pairs using Selective Epi Removal
摘要： We report on the demonstration of monolithically integrated light-emitting diode (LED) and quasi-vertical U-shaped trench-gate metal-oxide-semiconductor field-effect transistor (UMOSFET) in GaN. Selective epi removal (SER) approach was used on an LED-on-FET epi stack on sapphire substrates. Individual p-GaN layers were used for LED and FET in our design. LED light modulation by the supply voltage and the FET gate voltage was realized, and an integrated 350μm×350μm LED/UMOSFET pair exhibits a light output power (LOP) of 4.9 W/cm2 or 6.0 mW. An integrated device with a UMOSFET driving a 3-LED chain was also demonstrated. The normally-off power UMOSFET has a threshold voltage of 7 V, a breakdown voltage of 208 V, and a specific on-resistance of 23 mΩ-cm2, in which hexagonal cells were applied to obtain identical m-plane MOS gate interfaces. The effect of FET sizing on integrated pairs was also studied, and a trade-off model of FET/LED power ratio vs. FET/LED area ratio was created, which serves as universal criterion for FET/LED integration. The tested device with the best trade-off has FET/LED area ratio of 24% and FET/LED power ratio of 56%. This work creates a new building block for future GaN light-emitting integrated circuits (LEICs).
关键词： monolithic integration,FET/LED power ratio vs. area ratio trade-off,quasi-vertical power UMOSFET,LED,GaN
更新于2025-09-12 10:27:22
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Analysis on DC and AC Characteristics of Self Heating Effect in Nanowire
摘要： As devices are scaling down aggressively, three-dimensional field-effect transistors (FETs) becomes one of essential factors to obtain high gate controllability in order to reduce leakage current. However, insulators surrounding channel for above the reason block heat emission so that the lattice temperature can increase to the critical levels for devices. This phenomenon, called Self Heating Effect (SHE), can deteriorate device performance significantly. From this point of view, overall study on SHE in 5 nm node Nanowire FET (NWFET) was implemented by simulation. Through analysis on on-current (Ion), thermal resistance (Rth), transient characteristics, the DC and AC characteristics were investigated.
关键词： Thermal Resistance (Rth),Self Heating Effect (SHE),Nanowire FET (NWFET)
更新于2025-09-11 14:15:04
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Design and analysis of electrostatic-charge plasma based dopingless IGZO vertical nanowire FET for ammonia gas sensing
摘要： In this paper, Dopingless Gate All Around (GAA) Vertical Nanowire Field Effect Transistor (VNWFET) is designed with artificial material Indium Gallium Zinc Oxide (IGZO) as a channel material. IGZO channel has high electron mobility compared to more traditional amorphous semiconductors. In VNWFETs, since the channel length (Lch) is characterized vertically, it can be relaxed without area penalty on-chip, which in turn also allows some relaxation in the nanowire diameter while keeping optimum short-channel-effects control. Electrostatic-Charge Plasma technique is used to form a source-drain region on an intrinsic body of IGZO material. At the source side, the N+ region is formed by selecting the appropriate work function of the metal electrode, and at the drain side, the N+ region is formed by giving biasing to the metal electrode. N+ channel dopingless VNWFET with the catalytic metal gate is proposed for ammonia gas sensing. Cobalt, Molybdenum, and Ruthenium are used as a gate electrode in ammonia gas detection due to their high reactivity towards ammonia. Also, we have compared their ON and OFF sensitivity of the proposed device toward the gas adsorption. Due to the presence of gas on the gate, the metal work function of gate metal changes which varies the OFF-current (IOFF), ON-current (ION) and Threshold voltage (Vth) as these are considered as sensitivity parameters for sensing the ammonia gas molecules. The dimensional parameters (radius, and length) and dielectric materials are varied to check the change in device sensitivities. Results show that as the work function varies increases 50, 100, 150, 200meV and 250meV for catalytic metal at the gate, the sensitivity is increased.
关键词： Vertical nanowire FET (VNWFET),Indium Gallium Zinc Oxide (IGZO),Electrostatic-Charge Plasma (E-CP),Ammonia Gas sensor
更新于2025-09-10 09:29:36
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Simulation Model Development for Packaged Cascode Gallium Nitride Field-Effect Transistors
摘要： This paper presents a simple behavioral model with experimentally extracted parameters for packaged cascode gallium nitride (GaN) field-effect transistors (FETs). This study combined a level-1 metal–oxide–semiconductor field-effect transistor (MOSFET), a junction field-effect transistor (JFET), and a diode model to simulate a cascode GaN FET, in which a JFET was used to simulate a metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT). Using the JFET to simulate the MIS-HEMT not only ensures that the curve fits an S-shape transfer characteristic but also enables the pinch-off voltages extracted from the threshold voltage of the MIS-HEMT to be used as a watershed to distinguish where the drop in parasitic capacitance occurs. Parameter extraction was based on static and dynamic characteristics, which involved simulating the behavior of the created GaN FET model and comparing the extracted parameters with experimental measurements to demonstrate the accuracy of the simulation program with an integrated circuit emphasis (SPICE) model. Cascode capacitance was analyzed and verified through experimental measurements and SPICE simulations. The analysis revealed that the capacitance of low-voltage MOSFETs plays a critical role in increasing the overall capacitance of cascode GaN FETs. The turn-off resistance mechanism effectively described the leakage current, and a double-pulse tester was used to evaluate the switching performance of the fabricated cascode GaN FET. LTspice simulation software was adopted to compare the experimental switching results. Overall, the simulation results were strongly in agreement with the experimental results.
关键词： turn-off resistance,GaN FET,MIS-HEMT,SPICE,cascode,behavioral model,parasitic capacitance
更新于2025-09-10 09:29:36