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Keywords = vacuum field emission transistor

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11 pages, 1677 KiB  
Article
A Novel Darlington Structure Power Switch Using a Vacuum Field Emission Transistor
by Yulong Ding, Yanlin Ke, Juncong She, Yu Zhang and Shaozhi Deng
Electronics 2025, 14(9), 1737; https://doi.org/10.3390/electronics14091737 - 24 Apr 2025
Viewed by 384
Abstract
This study proposes a power switch combining a vacuum field emission transistor (VFET) as a controlled transistor with a power bipolar Darlington transistor (DT) as an output transistor, termed the VFET–DT structure. Compared to the MOS–bipolar Darlington power switch, the VFET–DT structure achieves [...] Read more.
This study proposes a power switch combining a vacuum field emission transistor (VFET) as a controlled transistor with a power bipolar Darlington transistor (DT) as an output transistor, termed the VFET–DT structure. Compared to the MOS–bipolar Darlington power switch, the VFET–DT structure achieves an extremely low off-state leakage current and high-voltage withstanding capability due to the field emission mechanism of the VFET. It can also avoid the Miller effect that results from incorporating the load resistance into the feedback loop. The high gain and high-power capacity can be achieved due to the cascade of DT. The device’s typical electrical characteristics were theoretically investigated by simulation. The VFET–DT structure exhibited a high-power capacity of 20 A and 400 V with a minimum conduction voltage drop of 1.316 V and a switching frequency of 100 kHz. The results demonstrated that the combination of a vacuum transistor and a solid-state transistor combines the advantages of both and benefits the performance of the power switch. Full article
(This article belongs to the Special Issue Vacuum Electronics: From Micro to Nano)
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16 pages, 3331 KiB  
Article
Piezo-VFETs: Vacuum Field Emission Transistors Controlled by Piezoelectric MEMS Sensors as an Artificial Mechanoreceptor with High Sensitivity and Low Power Consumption
by Chang Ge, Yuezhong Chen, Daolong Yu, Zhixia Liu and Ji Xu
Sensors 2024, 24(20), 6764; https://doi.org/10.3390/s24206764 - 21 Oct 2024
Cited by 1 | Viewed by 3694
Abstract
As one of the most promising electronic devices in the post-Moore era, nanoscale vacuum field emission transistors (VFETs) have garnered significant attention due to their unique electron transport mechanism featuring ballistic transport within vacuum channels. Existing research on these nanoscale vacuum channel devices [...] Read more.
As one of the most promising electronic devices in the post-Moore era, nanoscale vacuum field emission transistors (VFETs) have garnered significant attention due to their unique electron transport mechanism featuring ballistic transport within vacuum channels. Existing research on these nanoscale vacuum channel devices has primarily focused on structural design for logic circuits. Studies exploring their application potential in other vital fields, such as sensors based on VFET, are more limited. In this study, for the first time, the design of a vacuum field emission transistor (VFET) coupled with a piezoelectric microelectromechanical (MEMS) sensing unit is proposed as the artificial mechanoreceptor for sensing purposes. With a negative threshold voltage similar to an N-channel depletion-mode metal oxide silicon field effect transistor, the proposed VFET has its continuous current tuned by the piezoelectric potential generated by the sensing unit, amplifying the magnitude of signals resulting from electromechanical coupling. Simulations have been conducted to validate the feasibility of such a configuration. As indictable from the simulation results, the proposed piezoelectric VFET exhibits high sensitivity and an electrically adjustable measurement range. Compared to the traditional combination of piezoelectric MEMS sensors and solid-state field effect transistors (FETs), the piezoelectric VFET design has a significantly reduced power consumption thanks to its continuous current that is orders of magnitude smaller. These findings reveal the immense potential of piezoelectric VFET in sensing applications, building up the basis for using VFETs for simple, effective, and low-power pre-amplification of piezoelectric MEMS sensors and broadening the application scope of VFET in general. Full article
(This article belongs to the Special Issue Advanced Sensors in MEMS: 2nd Edition)
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10 pages, 4052 KiB  
Article
An In Situ Automated System for Real-Time Monitoring of Failures in Large-Scale Field Emitter Arrays
by Reza Farsad Asadi, Tao Zheng, Menglin Wang, Han Gao, Kenneth Sangston and Bruce Gnade
Instruments 2024, 8(4), 44; https://doi.org/10.3390/instruments8040044 - 6 Oct 2024
Cited by 1 | Viewed by 2067
Abstract
Nano-scale vacuum transistors (NVCTs) based on field emission have the potential to operate at high frequencies and withstand harsh environments, such as radiation, high temperatures, and high power. However, they have demonstrated instability and failures over time. To achieve high currents from NVCTs, [...] Read more.
Nano-scale vacuum transistors (NVCTs) based on field emission have the potential to operate at high frequencies and withstand harsh environments, such as radiation, high temperatures, and high power. However, they have demonstrated instability and failures over time. To achieve high currents from NVCTs, these devices are typically fabricated in large-scale arrays known as field emitter arrays (FEAs), which share a common gate, cathode, and anode. Consequently, the measured currents come from the entire array, providing limited information about the emission characteristics of individual tips. Arrays can exhibit nonuniform emission behavior across the emitting area. A phosphor screen can be used to monitor the emission pattern of the array. Additionally, visible damage can occur on the surface of the FEAs, potentially leading to the destruction of the gate and emitters, causing catastrophic failure of the FEAs. To monitor damage while operating the device, an ITO-coated glass anode, which is electrically conductive and visible-light-transparent, can be used. In this work, a method was developed to automatically monitor the emission pattern of the emitters and the changes in surface morphology while operating the devices and collecting electrical data, providing real-time information on the failure sequence of the FEAs. Full article
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13 pages, 3698 KiB  
Article
Proof-of-Concept Vacuum Microelectronic NOR Gate Fabricated Using Microelectromechanical Systems and Carbon Nanotube Field Emitters
by Tasso von Windheim, Kristin H. Gilchrist, Charles B. Parker, Stephen Hall, James B. Carlson, David Stokes, Nicholas G. Baldasaro, Charles T. Hess, Leif Scheick, Bernard Rax, Brian Stoner, Jeffrey T. Glass and Jason J. Amsden
Micromachines 2023, 14(5), 973; https://doi.org/10.3390/mi14050973 - 29 Apr 2023
Cited by 2 | Viewed by 2145
Abstract
This paper demonstrates a fully integrated vacuum microelectronic NOR logic gate fabricated using microfabricated polysilicon panels oriented perpendicular to the device substrate with integrated carbon nanotube (CNT) field emission cathodes. The vacuum microelectronic NOR logic gate consists of two parallel vacuum tetrodes fabricated [...] Read more.
This paper demonstrates a fully integrated vacuum microelectronic NOR logic gate fabricated using microfabricated polysilicon panels oriented perpendicular to the device substrate with integrated carbon nanotube (CNT) field emission cathodes. The vacuum microelectronic NOR logic gate consists of two parallel vacuum tetrodes fabricated using the polysilicon Multi-User MEMS Processes (polyMUMPs). Each tetrode of the vacuum microelectronic NOR gate demonstrated transistor-like performance but with a low transconductance of 7.6 × 10−9 S as current saturation was not achieved due to a coupling effect between the anode voltage and cathode current. With both tetrodes working in parallel, the NOR logic capabilities were demonstrated. However, the device exhibited asymmetric performance due to differences in the CNT emitter performance in each tetrode. Because vacuum microelectronic devices are attractive for use in high radiation environments, to test the radiation survivability of this device platform, we demonstrated the function of a simplified diode device structure during exposure to gamma radiation at a rate of 45.6 rad(Si)/second. These devices represent a proof-of-concept for a platform that can be used to build intricate vacuum microelectronic logic devices for use in high-radiation environments. Full article
(This article belongs to the Special Issue On-Chip Electron Emission and Related Devices)
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9 pages, 2280 KiB  
Article
A Vacuum Transistor Based on Field-Assisted Thermionic Emission from a Multiwalled Carbon Nanotube
by Yidan He, Zhiwei Li, Shuyu Mao, Fangyuan Zhan and Xianlong Wei
Electronics 2022, 11(3), 399; https://doi.org/10.3390/electronics11030399 - 28 Jan 2022
Cited by 7 | Viewed by 5373
Abstract
Vacuum triodes have been scaled down to the microscale on a chip by microfabrication technologies to be vacuum transistors. Most of the reported devices are based on field electron emission, which suffer from the problems of unstable electron emission, poor uniformity, and high [...] Read more.
Vacuum triodes have been scaled down to the microscale on a chip by microfabrication technologies to be vacuum transistors. Most of the reported devices are based on field electron emission, which suffer from the problems of unstable electron emission, poor uniformity, and high requirement for operating vacuum. Here, to overcome these problems, a vacuum transistor based on Field-Assisted thermionic emission from individual carbon nanotubes is proposed and fabricated using microfabrication technologies. The carbon nanotube vacuum transistor exhibits an ON/OFF current ratio as high as 104 and a subthreshold slope of ~4 V·dec−1. The gate controllability is found to be strongly dependent on the distance between the collector electrodes and electron emitter, and a device with the distance of 1.5 μm shows a better gate controllability than that with the distance of 0.5 μm. Benefiting from Field-Assisted thermionic emission mechanism, electric field required in our devices is about one order of magnitude smaller than that in the devices based on field electron emission, and the surface of the emitters shows much less gas molecule absorption than cold field emitters. These are expected to be helpful for improving the stability and uniformity of the devices. Full article
(This article belongs to the Special Issue High-Frequency Vacuum Electron Devices)
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11 pages, 2596 KiB  
Article
Air Pressure, Gas Exposure and Electron Beam Irradiation of 2D Transition Metal Dichalcogenides
by Antonio Di Bartolomeo, Aniello Pelella, Alessandro Grillo, Francesca Urban and Filippo Giubileo
Appl. Sci. 2020, 10(17), 5840; https://doi.org/10.3390/app10175840 - 23 Aug 2020
Cited by 6 | Viewed by 3018
Abstract
In this study, we investigate the electrical transport properties of back-gated field-effect transistors in which the channel is realized with two-dimensional transition metal dichalcogenide nanosheets, namely palladium diselenide (PdSe2) and molybdenum disulfide (MoS2). The effects of the environment (pressure, [...] Read more.
In this study, we investigate the electrical transport properties of back-gated field-effect transistors in which the channel is realized with two-dimensional transition metal dichalcogenide nanosheets, namely palladium diselenide (PdSe2) and molybdenum disulfide (MoS2). The effects of the environment (pressure, gas type, electron beam irradiation) on the electrical properties are the subject of an intense experimental study that evidences how PdSe2-based devices can be reversibly tuned from a predominantly n-type conduction (under high vacuum) to a p-type conduction (at atmospheric pressure) by simply modifying the pressure. Similarly, we report that, in MoS2-based devices, the transport properties are affected by pressure and gas type. In particular, the observed hysteresis in the transfer characteristics is explained in terms of gas absorption on the MoS2 surface due to the presence of a large number of defects. Moreover, we demonstrate the monotonic (increasing) dependence of the width of the hysteresis on decreasing the gas adsorption energy. We also report the effects of electron beam irradiation on the transport properties of two-dimensional field-effect transistors, showing that low fluences of the order of few e-/nm2 are sufficient to cause appreciable modifications to the transport characteristics. Finally, we profit from our experimental setup, realized inside a scanning electron microscope and equipped with piezo-driven nanoprobes, to perform a field emission characterization of PdSe2 and MoS2 nanosheets at cathode–anode separation distances as small as 200 nm. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Materials)
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9 pages, 3003 KiB  
Article
Fermi-Level Pinning Mechanism in MoS2 Field-Effect Transistors Developed by Thermionic Emission Theory
by Yu Zhang, Xiong Chen, Hao Zhang, Xicheng Wei, Xiangfeng Guan, Yonghua Wu, Shaozu Hu, Jiale Zheng, Guidong Wang, Jiawen Qiu and Jun Wang
Appl. Sci. 2020, 10(8), 2754; https://doi.org/10.3390/app10082754 - 16 Apr 2020
Cited by 8 | Viewed by 4795
Abstract
Molybdenum disulfide (MoS2) field-effect transistors (FETs) with four different metallic electrodes (Au,Ag,Al,Cu) of drain-source were fabricated by mechanical exfoliation and vacuum evaporation methods. The mobilities of the devices were (Au) 21.01, (Ag) 23.15, (Al) 5.35 and (Cu) 40.52 cm2/Vs, [...] Read more.
Molybdenum disulfide (MoS2) field-effect transistors (FETs) with four different metallic electrodes (Au,Ag,Al,Cu) of drain-source were fabricated by mechanical exfoliation and vacuum evaporation methods. The mobilities of the devices were (Au) 21.01, (Ag) 23.15, (Al) 5.35 and (Cu) 40.52 cm2/Vs, respectively. Unpredictably, the on-state currents of four devices were of the same order of magnitude with no obvious difference. For clarifying this phenomenon, we calculated the Schottky barrier height (SBH) of the four metal–semiconductor contacts by thermionic emission theory and confirmed the existence of Fermi-level pinning (FLP). We suppose the FLP may be caused by surface states of the semiconductor produced from crystal defects. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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12 pages, 4888 KiB  
Article
Vertical Field Emission Air-Channel Diodes and Transistors
by Wen-Teng Chang, Hsu-Jung Hsu and Po-Heng Pao
Micromachines 2019, 10(12), 858; https://doi.org/10.3390/mi10120858 - 6 Dec 2019
Cited by 22 | Viewed by 4256
Abstract
Vacuum channel transistors are potential candidates for low-loss and high-speed electronic devices beyond complementary metal-oxide-semiconductors (CMOS). When the nanoscale transport distance is smaller than the mean free path (MFP) in atmospheric pressure, a transistor can work in air owing to the immunity of [...] Read more.
Vacuum channel transistors are potential candidates for low-loss and high-speed electronic devices beyond complementary metal-oxide-semiconductors (CMOS). When the nanoscale transport distance is smaller than the mean free path (MFP) in atmospheric pressure, a transistor can work in air owing to the immunity of carrier collision. The nature of a vacuum channel allows devices to function in a high-temperature radiation environment. This research intended to investigate gate location in a vertical vacuum channel transistor. The influence of scattering under different ambient pressure levels was evaluated using a transport distance of about 60 nm, around the range of MFP in air. The finite element model suggests that gate electrodes should be near emitters in vertical vacuum channel transistors because the electrodes exhibit high-drive currents and low-subthreshold swings. The particle trajectory model indicates that collected electron flow (electric current) performs like a typical metal oxide semiconductor field effect-transistor (MOSFET), and that gate voltage plays a role in enhancing emission electrons. The results of the measurement on vertical diodes show that current and voltage under reduced pressure and filled with CO2 are different from those under atmospheric pressure. This result implies that this design can be used for gas and pressure sensing. Full article
(This article belongs to the Special Issue Miniaturized Transistors, Volume II)
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12 pages, 7023 KiB  
Article
A Novel, Hybrid-Integrated, High-Precision, Vacuum Microelectronic Accelerometer with Nano-Field Emission Tips
by Haitao Liu, Kai Wei, Zhengzhou Li, Wengang Huang, Yi Xu and Wei Cui
Micromachines 2018, 9(10), 481; https://doi.org/10.3390/mi9100481 - 20 Sep 2018
Cited by 7 | Viewed by 4140
Abstract
In this paper, a novel, hybrid-integrated, high-precision, vacuum microelectronic accelerometer is put forward, based on the theory of field emission; the accelerometer consists of a sensitive structure and an ASIC interface (application-specific integrated circuit). The sensitive structure has a cathode cone tip array, [...] Read more.
In this paper, a novel, hybrid-integrated, high-precision, vacuum microelectronic accelerometer is put forward, based on the theory of field emission; the accelerometer consists of a sensitive structure and an ASIC interface (application-specific integrated circuit). The sensitive structure has a cathode cone tip array, a folded beam, an emitter electrode, and a feedback electrode. The sensor is fabricated on a double-sided polished (1 0 0) N-type silicon wafer; the tip array of the cathode is shaped by wet etching with HNA (HNO3, HF, and CH3COOH) and metalized by TiW/Au thin film. The structure of the sensor is finally released by the ICP (inductively coupled plasma) process. The ASIC interface was designed and fabricated based on the P-JFET (Positive-Junction Field Effect Transistor) high-voltage bipolar process. The accelerometer was tested through a static field rollover test, and the test results show that the hybrid-integrated vacuum microelectronic accelerometer has good performance, with a sensitivity of 3.081 V/g, the non-linearity is 0.84% in the measuring range of −1 g~1 g, the average noise spectrum density value is 36.7 μV/ Hz in the frequency range of 0–200 Hz, the resolution of the vacuum microelectronic accelerometer can reach 1.1 × 10−5 g, and the zero stability reaches 0.18 mg in 24 h. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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