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On June 1, 2022, the Department of Electronics, Oscillations and Waves of SSU turned 70 years old. Over the years, the Department has passed a brilliant way. Three of its leaders at different times were rectors of Saratov State University. Graduates and staff of the department are known in the scientific world not only in our country, but also far beyond its borders. We pay tribute to the Department of Electronics and remember the events, as well as all those people with whom we were somehow connected within its walls, and whose memory will remain in our hearts for a long time.

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. [ABSTRACT FROM AUTHOR]

Glow discharge with electrostatic confinement of electrons in a vacuum chamber allows plasma processing of conductive products in a wide pressure range of p = 0.01 – 5 Pa. To assist processing of a small dielectric product with a concentrated on its surface beam of fast neutral atoms, which do not cause charge effects, ions from the discharge plasma are accelerated towards the product and transformed into fast atoms. The beam is produced using a negatively biased cylindrical or a spherical grid immersed in the plasma. Ions accelerated by the grid turn into fast neutral atoms at p > 0.1 Pa due to charge exchange collisions with gas atoms in the space charge sheaths adjoining the grid. The atoms form a diverging neutral beam and a converging beam propagating from the grid in opposite directions. The beam propagating from the concave surface of a 0.24-m-wide cylindrical grid is focused on a target within a 10-mm-wide stripe, and the beam from the 0.24-mdiameter spherical grid is focused within a 10-mm-diameter circle. At the bias voltage U=5 kV and p~0.1 Pa, the energy of fast argon atoms is distributed continuously from zero to eU~5 keV. The pressure increase to 1 Pa results in the tenfold growth of their equivalent current and a decrease in the mean energy by an order of magnitude, which substantially raises the efficiency of material etching. Sharpening by the beam of ceramic knife-blades proved that the new method for the generation of concentrated fast atom beams can be effectively used for the processing of dielectric materials in vacuum. [ABSTRACT FROM AUTHOR]

The School of Corresponding Member of the Russian Academy of Sciences, Doctor of Physical and Mathematical Sciences, Professor Dmitry Ivanovich Trubetskov is a unique phenomenon widely known to the scientific community both in Russia and abroad. Its includes science, education and a lot of educational activities. The uniqueness of the School of D. I. Trubetskov is that it covers a wide range of current scientific areas: vacuum electronics, magnetoelectronics, nonlinear dynamics, etc. The School of D. I. Trubetskov is still a wide range of events, the participants of which are young scientists who make scientific reports, and lecturers are world-renowned scientists. Among such events, we would especially like to highlight the Winter Schools-Seminars on Microwave Electronics for Engineers and Scientists, held since 1970 with a periodicity of 2–3 years, and the International Scientific School “Chaotic oscillations and waves – CHAOS”, held since 1985 with a periodicity of 3 years. In 1988 D. I. Trubetskov organizes the first scientific school for schoolchildren “Oscillations, Waves, Electrons”, held at intervals of 2 years. Since 1997 the school has been called “Nonlinear days in Saratov for young people”. Since 1995, the Scientific School of D. I. Trubetskov was recognized as the winner of the competition for the title of the leading Scientific School in Russia five times.

Thermionic emission is a tunneling phenomenon, which depicts that electrons on the surface of a conductor can be pulled out into the vacuum when they are subjected to high electrical tensions while being heated hot enough to overtake their work functions. This principle has led to the great success of the so-called vacuum tubes in the early 20th century. To date, major challenges still remain in the miniaturization of a vacuum channel transistor for on-chip integration in modern solid-state integrated circuits. Here, by introducing nano-sized vacuum gaps (∼ 200 nm) in a van der Waals heterostructure, we successfully fabricated a one-dimensional (1D) edge-to-edge thermionic emission vacuum tube using graphene as the filament. With the increasing collector voltage, the emitted current exhibits a typical rectifying behavior, with the maximum emission current reaching 200 pA and an ONâ€"OFF ratio of 103. In addition, it is found that the maximum emission current is proportional to the number of the layers of graphene. Our results expand the research of nano-sized vacuum tubes to an unexplored physical limit of 1D edge-to-edge emission, and hold great promise for future nano-electronic systems based on it. [ABSTRACT FROM AUTHOR]

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.

In optical detection setups to measure the deflection of micro-cantilevers, part of the sensing light is absorbed, heating the mechanical probe. We present experimental evidences of a frequency shift of the resonant modes of a cantilever when the light power of the optical measurement set-up is increased. This frequency shift is a signature of the temperature rise and presents a dependence on the mode number. An analytical model is derived to take into account the temperature profile along the cantilever; it shows that the frequency shifts are given by an average of the profile weighted by the local curvature for each resonant mode. We apply this framework to measurements in vacuum and demonstrate that huge temperatures can be reached with moderate light intensities: a 1000 °C with little more than 10 mW. We finally present some insight into the physical phenomena when the cantilever is in air instead of vacuum. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate suspended two- and four-terminal field emission devices for high-temperature operation. The planar structures were fabricated with tungsten on a 200-nm silicon nitride membrane. The insulator in the vicinity of the terminals was removed to minimize undesirable Frenkel–Poole emission and increase the resistance of leakage current pathways. The effects of temperatures up to 450 °C on Fowler–Nordheim emission characteristics and parasitic leakage resistance were studied. Turn-on voltages with magnitudes under 15 V that further decreased as a function of increasing temperature for the two-terminal device were reported. Gating at temperatures of 150 °C and 300 °C was shown for the four-terminal device, and corresponding transconductance and cutoff frequency values were computed. [ABSTRACT FROM AUTHOR]

Vacuum-sealed fully integrated diode and triode field emission arrays based on Ti Spindt-type field emitters have been developed in a scalable, CMOS-compatible process directly on Si. Diode characterization in air demonstrates effective vacuum sealing and field emission conduction, with current drivability that scales with array size. Triode characterization in vacuum demonstrates gate-modulated field emission of the output current and highlights new effects observed in a fully integrated geometry with closely spaced electrodes. Demonstrating up to 200-V blocking voltage and similar magnitude punchthrough voltages, the arrays can be utilized as high-voltage devices in CMOS applications or with microelectromechanical systems (MEMS) technologies using post-CMOS MEMS integration techniques. Low-temperature measurements reveal areas of improvement for electrode isolation; combined with the use of improved cathode materials, these devices have the potential to be used in high-power applications. [ABSTRACT FROM AUTHOR]

We demonstrate high-density (1-μm pitch) silicon field-ionization arrays (FIAs) with self-aligned gate apertures (350 nm in diameter) and integrated nanowire current regulators. Our FIAs achieved high field factors (>0.1 nm−1) and significantly lower ionization voltages (<100 V) than the devices with lower tip densities previously reported. Ion currents were measured in argon, deuterium, and helium at pressures from 1 to 16 mTorr. The FIAs turned on between 70 and 85 V, and the ion currents of around 0.4 nA were measured at 100 V. Higher currents of 7 nA were obtained at 147 V and 16 mTorr, but with the risk of gate damage by the ions energized in the intense gate-ionizer field. Si FIAs coated with Pt resulted in higher field factors due to sharper tips, but lower ion currents. Surface states, coupled with molecular adsorption and transport to the ionizer, are the possible mechanisms for lower voltage ionization in the uncoated Si FIAs. [ABSTRACT FROM AUTHOR]

The article studies a triode for vacuum microelectronics with horizontal geometry (planar triode). A simple theoretical model of the device is proposed and the minimum cutoff voltage is calculated. Experiments are carried out on the fundamental model of the device, which qualitatively confirm the main theoretical conclusions. [ABSTRACT FROM AUTHOR]

Plasma transport in a hybrid dc vacuum arc plasma source for ion deposition and plasma immersion treatment is considered. It is found that external crossed electric and magnetic fields near the substrate can significantly reduce the relative amplitude of ion current fluctuations Īf at the substrate surface. In particular, Īf decreases with the applied magnetic field when the bias voltage exceeds 300 V, thus allowing one to reduce the deviations from the rated process parameters. This phenomenon can be attributed to an interaction between the metal-plasma jet from the arc source and the discharge plasma in the crossed fields. [ABSTRACT FROM AUTHOR]

A fully integrated on-chip vacuum microtriode using carbon nanotubes as field emitters was constructed laterally on a silicon surface using microelectrical mechanical systems (MEMS) design and fabrication principles. Each electrode in the triode was made of a hinged polycrystalline silicon panel that could be rotated and locked into an upright position. The device was operated at a current density as high as 16 A/cm2. Although the transconductance was measured only at 1.3 S, the dc output power delivered at the anode was almost 40 more than the power lost at the grid electrode. The technique combines high-performance nanomaterials with mature solid-state fabrication technology to produce miniaturized power-amplifying vacuum devices in an on-chip form, which could potentially offer a route of integrating vacuum and solid-state electronics and open up new applications for “old fashioned” vacuum tubes.

In recent years, small-size, low-weight aerospace propulsion systems have developed rapidly for space exploration, on-orbit scientific instruments and extra space missions, while additional electron emission devices are commonly required in those propulsion systems. Carbon nanotube (CNT) based field emission cathodes exhibit extraordinary field emission properties and are regarded to be an ideal alternative of conventional thermionic or hollow cathodes. In this study, the authors give an overview of present status of researches on CNT-based electron emission cathodes for utilising as neutralisers or electron sources particularly in space electric propulsion systems, the theory and characteristics of CNT are also illustrated. Furthermore, challenges, problems and possible solutions before actual applications of CNT in a space mission are discussed accordingly.

Two variants of schemes of a multibeam vircator are proposed and studied in this paper. Numerical analysis of the influence of various parameters of these systems (magnitude of the external magnetic field and detuning of beam currents) on the generation characteristics was conducted. The possibility of synchronizing several virtual cathodes in a single drift space of a multibeam vircator is demonstrated. The regime maps of basic control parameters of the system are built. The possibility of effective interaction of several virtual cathodes in a single drift space is analyzed, and the conditions for implementing an effective addition of powers of each beam at the output load are determined. [ABSTRACT FROM AUTHOR]

Slow-wave structure (SWS) is a core part of a traveling-wave-tube (TWT) amplifier. In this letter, the planar microstrip meander SWS on a dielectric substrate at $V$ -band (50–70 GHz) is studied. The basic electromagnetic parameters of the SWS are calculated. The SWS circuits are designed and fabricated, and good transmission characteristics are measured. The SWS developed is characterized by a wide bandwidth and a relatively-large slow-wave factor, and is suitable for a low-voltage TWT with the sheet electron beam. [ABSTRACT FROM AUTHOR]

Large-signal analysis is presented for analysing non-linear beam-wave interaction in a planar THz TWT with a sheet electron beam. The sheet beam within one RF beam wavelength is represented by uniform rectangular charged discs for confined flow of the beam, and the discs are tracked in small distance steps of forward integration. For a planar THz TWT, a staggered double-vane loaded rectangular waveguide slow-wave structure (SDVSWS) is used. Frequency-domain analysis is used to define the RF circuit field in the SDVSWS and the interaction of the RF circuit field with the electron beam is carried out for steady-state TWT operation. The RF circuit field is considered to be continuous as in a helix SWS and it is represented by transmission line theory at each integration plane. A large-signal analysis code of a helix TWT with pencil beam (SUNRAY-1D) was modified for a planar TWT with a sheet beam. The accuracy of the modified SUNRAY code was checked against the 3D e.m. field simulator (CST-PS) by comparing the output performance for a 0.22-THz planar TWT. The results for the gain and the output power over the operating band given by the two codes were found to be comparable. A significant advantage of the SUNRAY code is that it is very fast compared to the CST code. It takes less than a minute to simulate the RF performance of a typical THz TWT at a single frequency and drive power on a standard PC. The SUNRAY code can therefore, be used interactively for design a complete SWS with input/output couplers, sever, loss profiles and phase velocity taper for a high efficiency high gain THz TWT. [ABSTRACT FROM PUBLISHER]

In this paper, a U-shaped meander-line slow-wave structure (SWS) with stub-loading is proposed for applications in Ka-band traveling-wave tube (TWT). This new slow-wave structure, loaded with a stub at the center of the U-turn section, has higher interaction impedance and lower phase velocity compared with conventional U-shaped meander-line SWSs, indicating that the devices based on this structure may have a lower operating voltage and higher output power. The dispersion characteristic, interaction impedance, transmission characteristics, and beam-wave interaction are simulated by utilizing simulation tool. The simulation result predicts that the millimeter-wave traveling-wave tube design based on this slow-wave structure is capable of delivering over 200 W with a gain of 33 dB and interaction efficiency 14.5% at the center frequency 34 GHz. This design, more compact and powerful in comparison with those based on more conventional vacuum electronic mechanisms, is demonstrated as a prospective option for integrated millimeter-wave power modules (MMPMs) empowering a broad spectrum of fields, from target detection, to imaging and telecommunications, among others. [ABSTRACT FROM AUTHOR]

As a key refractory carbide, hafnium carbide (HfC) is commonly used as structural materials while the field emission (FE) application of HfC in the field of vacuum microelectronics is almost the only one for functional material purposes. Based on its outstanding physical and chemical characteristics, HfC is identified as a potential candidate with satisfactory mechanical properties and long-term and/or high-temperature FE stability for future applications in high-performance field emitters. However, the development of HfC in various FE applications is hindered because it is not facile to fabricate large-scale low-dimensional HfC field nanoemitters. Herein, High-aspect-ratio HfC nanobelts accompanied by HfC nanowires were synthesized on a large scale by a traditional and simple catalytic chemical vapor deposition (CVD) method. Classical vapor–liquid–solid (VLS) theory was employed to explain the growth of the HfC nanowires and nanobelts along axial direction. The thin HfO 2 shell and thin C layer surrounding the nanostructures might give rise to the diameter fluctuation of HfC nanowires and the width increase of HfC nanobelts in lateral direction. Field emission results show that the high-aspect-ratio HfC nanobelts accompanied by the nanowires are promising field nanoemitters, which exhibit excellent field emission properties with a fairly low turn-on field of ∼1.5 V μm −1 and a low current fluctuation less than ∼10%. This suggests that HfC ceramics with high-aspect-ratio nanostructures are ideal cathode material for various field emission applications. [ABSTRACT FROM AUTHOR]

The growth of carbon nanotubes (CNTs) on polycrystalline silicon substrates was studied to improve the design of CNT field emission sources for microelectromechanical systems (MEMS) applications and vacuum microelectronic devices (VMDs). Microwave plasma-enhanced chemical vapor deposition (PECVD) was used for CNT growth, resulting in CNTs that incorporate the catalyst particle at their base. The kinetics of CNT growth on polysilicon were compared to growth on Si (100) using the model of Deal and Grove, finding activation energies of 1.61 and 1.54 eV for the nucleation phase of growth and 1.90 and 3.69 eV for the diffusion-limited phase on Si (100) and polysilicon, respectively. Diffusivity values for growth on polysilicon were notably lower than the corresponding values on Si (100) and the growth process became diffusion-limited earlier. Evidence favors a surface diffusion growth mechanism involving diffusion of carbon precursor species along the length of the CNT forest to the catalyst at the base. Explanations for the differences in activation energies and diffusivities were elucidated by SEM analysis of the catalyst nanoparticle arrays and through wide-angle X-ray scattering (WAXS) of CNT forests. Finally, methods are presented to improve adhesion of CNT films during operation as field emitters, resulting in a 2.5× improvement. [ABSTRACT FROM AUTHOR]

A novel high-precision vacuum microelectronic accelerometer has been successfully fabricated and tested in our laboratory. This accelerometer has unique advantages of high sensitivity, fast response, and anti-radiation stability. It is a prototype intended for navigation applications and is required to feature micro-g resolution. This paper briefly describes the structure and working principle of our vacuum microelectronic accelerometer, and the mathematical model is also established. The performances of the accelerometer system are discussed after Matlab modeling. The results show that, the dynamic response of the accelerometer system is significantly improved by choosing appropriate parameters of signal detecting circuit, and the signal detecting circuit is designed. In order to attain good linearity and performance, the closed-loop control mode is adopted. Weak current detection technology is studied, and integral T-style feedback network is used in I/V conversion, which will eliminate high-frequency noise at the front of the circuit. According to the modeling parameters, the low-pass filter is designed. This circuit is simple, reliable, and has high precision. Experiments are done and the results show that the vacuum microelectronic accelerometer exhibits good linearity over -1 g to +1 g, an output sensitivity of 543 mV/g, and a nonlinearity of 0.94 %.

The present study describes a sputtering and in situ vacuum electrical resistivity setup that allows a more efficient sputtering-oxidation coupling process for the fabrication of oxide compounds like vanadium dioxide, VO2. After the sputtering deposition of pure V thin films, the proposed setup enables the sample holder to be transferred from the sputtering to the in situ annealing + resistivity chamber without venting the whole system. The thermal oxidation of the V films was studied by implementing two different temperature cycles up to 550 °C, both in air (using a different resistivity setup) and vacuum conditions. Main results show that the proposed system is able to accurately follow the different temperature setpoints, presenting clean and low-noise resistivity curves. Furthermore, it is possible to identify the formation of different vanadium oxide phases in air, taking into account the distinct temperature cycles used. The metallic-like electrical properties of the annealed coatings are maintained in vacuum whereas those heated in air produce a vanadium oxide phase mixture. [ABSTRACT FROM AUTHOR]

Field Emission devices (FE) have been proposed as efficient electron sources for several applications such as electron microscopy and vacuum sensors. Evidently, characterization methods applied during development phase of FE devices are crucial to evaluate aspects related with their working stability, homogeneity, and efficiency. However, the traditional methods provide only overall information about such characteristics, which difficult to improve the performance of these devices and their integration with electronics. To overcome this problem, this work presents an alternative system to characterize FE devices through electron emission imaging in real-time. The proposed system acquires I - V features of FE devices, while a video camera captures the emission image from a phosphor screen. Virtual instrumentation based on LabVIEW manages the whole system including measurement instruments, image capture, and data processing. As a result, histograms, 3D maps, and other FE analyses provide information about emitting characteristics of selected regions of interest. The main contribution of this work is to offer an important tool for the analyses of electron emission, by the association of captured images with the localized emission current. The extracted information from our system can efficiently support the characterization and the development of FE devices. [ABSTRACT FROM AUTHOR]

Silicon carbide field emission arrays (FEA) are at the forefront of development as new promising electron sources for vacuum microelectronic devices. The authors present a new process for the fabrication of array of nanoscale tips with reduced heterogeneity of their heights. The characterization results show that at strong electric fields the heterogeneity is a key factor causing current instability. Diamond is recognized as the best material to obtain field emission, but fabrication of tip array with a reasonable aspect ratio is a challenge. Therefore, the authors have combined the benefits of both the abovementioned materials and fabricated silicon carbide FEA of tips coated with nanocrystalline undoped diamond thin film. The coating smoothens the virtual emitting surface connecting the tips, and therefore reduces heterogeneity of their heights, thereby improving the current stability. Current fluctuation decreased to 5% in compare with 23% in FEA without coating. [ABSTRACT FROM AUTHOR]

The movement from discrete transistors to integrated silicon circuits led to the rapid evolution of microscale electronics, but there has been no equivalent transition for the vacuum tube transistor. Difficulty integrating devices at microscales has hindered the use of vacuum electronic circuits, despite the unique advantages they offer in selected applications. The development of the field emission microfabricated cathode offers the potential to take advantage of the benefits of the vacuum technology in an integrated platform. This paper utilizes an MEMS carbon nanotube field emission vacuum microelectronic device as an active circuit element. Using a combination of particle trajectory simulation and experimental characterization, we investigated device performance in an integrated platform. Specifically, we present solutions for the operation of multiple devices in close proximity and for enhancing transmission (i.e., reducing grid loss) in vacuum field emission devices. The isolation structures reduced the crosstalk between neighboring devices from 14% on average, to nearly zero. Innovative geometries and a new operational mode reduced the grid loss by nearly three times, improving transmission of the current from the cathode to the anode from 25% from the previous designs to 70% on average. These performance enhancements are the important enablers for larger scale integration and for the realization of complex vacuum microelectronic circuits. [ABSTRACT FROM AUTHOR]

We have developed a simple and effective method to improve field emission (FE) performance of SnO nanowire arrays (SnO NWs) decorated with low-cost CNTs and conducting Au nanoparticles. SnO NWs was grown on carbon fibers (CF) using Au-assisted vapor liquid solid method. CNT and Au nanoparticle decoration of SnO NWs was obtained by subsequent decoration via spray-coating and sputtering deposition process. Compared with the as-prepared SnO and CNT/SnO, Au/CNT/SnO composite emitters have exhibited predominant FE characteristics with low turn-on field (0.72 V/μm), high field enhancement factor (~5726), and good stability. The FE enhancement was attributed to highly conducted Au nanoparticles and CNTs with sharp tips densely distributed on the surface of SnO NWs, which can effectively increase emission site density, favor electron transfer and quickly transmit heat from the emitters to substrate. Our results revealed that Au/CNT/SnO composite with excellent FE performance grown on CF can provide the possibility of application in flexible flat panel displays. [ABSTRACT FROM AUTHOR]

This paper describes a particular design of a thermionic electron gun employable in Sub-millimetric waves vacuum tubes and for spatial environment applications. Design strategies are proposed by providing closed formulas and dimensioning techniques. A multiphysics approach has been employed for studying the effect of multiple physics influencing factors due to the cathode heating over the beam dynamics. Operating temperature, thermal expansion displacements and external environment effects have been considered. This paper would give the academic knowledge for developing electron sources with narrow dimension providing an analytical approach followed by numerical modeling technique for virtual prototypes, which foresee the global behavior of this kind of devices while operating. For this aim, several strategies have been adopted and described in detail to obtain a simple model, which shows clearly these effects and their relations. The proposed modeling can allow for the correct operation in this range of narrow dimensions, where the operation is extremely critical while the cathode heating effects are present. According to this study, the appropriate materials and geometrical shapes for the beam-forming electrodes can be chosen. [ABSTRACT FROM AUTHOR]

A graphene-based vacuum transistor (GVT) with a high ON/OFF current ratio is proposed and experimentally realized by employing electrically biased graphene as the electron emitter. The states of a GVT are switched by tuning the bias voltage applied to the graphene emitter with an ON/OFF current ratio up to 106, a subthreshold slope of 120 mV dec−1 and low working voltages of <10 V, exhibiting switching performances superior to those of previously reported graphene-based solid-state transistors. GVTs are fabricated and integrated using silicon microfabrication technology. A perfectly symmetric ambipolar device is achieved by integrating two GVTs, implying the potential of realizing vacuum integrated circuits based on GVTs. GVTs are expected to find applications in extreme environments such as high temperature and intense irradiation. [ABSTRACT FROM AUTHOR]

Tunneling (cold emission) through potential barriers of a complex shape in vacuum microelectronic diode and triode structures, including those with several electrodes, is theoretically investigated and I- V characteristics of these structures are obtained. [ABSTRACT FROM AUTHOR]

Simulations have shown that space-charge effects can lead to regular modulation of photoemitted beams in vacuum diodes with gap sizes on the order of 1 $\mu $ m and accelerating voltage on the order of 1 V. These modulations are in the terahertz regime and can be tuned by simply changing the emitter area or accelerating vacuum field. The average current in the diode corresponds to the Child-Langmuir current, but the amplitude of the oscillations is affected by various factors. Given the small size and voltage of the system, the maximum radiated ac power is expected to be small. In this paper, we show that an array of small emitters produces higher frequency signals than a single large emitter of the same area and how these emitters may be synchronized to produce higher power signals. [ABSTRACT FROM PUBLISHER]

Electron hop funnels have been simulated using the new version of the particle trajectory simulation software, Lorentz-2E. Simulations were conducted to determine the validity of the version 9.2 results and the consistency of the results with a previous version of the software, version 8. In addition, a new method of injecting a uniform current with all rays of equal charge is discussed, and the results of the method are presented. Version 9.2 of the software was successfully implemented and a new emission model was tested. The transition of the software version will allow for faster simulation times of the electron hop funnel simulations to increase the understanding of the device. [ABSTRACT FROM AUTHOR]

A number of new technologies require conical and sharp tips to serve as electron emitters in the vacuum microelectronics. In this paper, we improved radius of curvature, height and cone angle of emitters in order to reach the enhancement result of field enhancement factor (β). We developed a fabrication process to improve geometry of emitter by employing isotropic dry etching in pure SF and a mixture of SF and O followed by thermal oxidation technique. We successfully achieved excellent conical emitters with 5-10 nm radius of curvature, 4.4 μm height, and 30° cone angle. The conical silicon emitters current-voltage characteristics shows that E = 4.8 V/μm (turn-on electric field) with current density of 10 μA/cm, and maximum current density J = 60.4 μA/cm at E = 8.14 V/μm. This study may provide a practical guideline for design and fabrication of a high-performance silicon emitter used in various industrial applications. [ABSTRACT FROM AUTHOR]

Insulating funnels, called electron hop funnels, use secondary electron emission and an electric field created by an electrode to transport current through the device. The surface charge along the funnel wall self-adjusts to get unity-gain transmission. Electron hop funnels allow increased control over the spatial and energy uniformity of the transmitted beam from a field emitter array. Measurements performed on the relationship between transmission through the device and the electrode voltage has shown hysteresis. To better understand the origin of the hysteresis, simulations have been performed using the particle trajectory code Lorentz 2E. The simulations reveal two very important mechanisms that define the transmission through the funnel. The simulations also show that hysteresis is a fundamental characteristic of hop funnels. [ABSTRACT FROM PUBLISHER]