Cross Section Of Electron Beam Research Articles

Study and comparison of resist characteristics for different negative tone electron beam resists

In this work, four types of negative electron beam resists are investigated. Electron beam lithography (EBL) experiments were conducted using EBL system ZBA23 (Raith) with the variable-shaped electron beam cross-section at 40 keV electron energy. Important electron beam resist characteristics such as sensitivity, dissolution rate, aspect ratio and sidewall developed profiles in the chemically amplified resist (CAR) SU-8 2000, non-CARs ma-N 2410 and ARN-7520, and inorganic negative resist HSQ XR-1514 are studied and compared. This study was motivated by the selection of a suitable resist for practical use such as large area gratings fabrication for optoelectronics.

Bipolar resistive switching in memristors based on Ge/Si(001) epitaxial layers

The Ag/Ge/Si(001) stacks with threading dislocations in Ge layer demonstrating the I-V curves typical for the bipolar resistive switching were investigated. Cross-sectional transmission electron microscopy and electron beam induced current measurement confirmed the resistive switching mechanism to be the formation of conductive filaments consisting of the Ag atoms across the entire Ge layer via the electric-field driven transport of Ag+ ions along the threading dislocations.

Effect of Electron Beam Velocity Spread in a Clinotron

We have studied the effect of velocity spread in the electron beam cross section on the output power, frequency, and starting current in a clinotron. It was shown that in the case when the lower electron layers move faster than upper ones there is an increase in the output power compared to the single velocity beam case. In the opposite case of faster upper layers, the output power decreases drastically and both the starting current and probability of multifrequency oscillations increase.

Investigation of the space-time stability of a large cross section electron beam generated by an accelerator with a grid plasma cathode

In an electron source with a grid plasma cathode on the basis of a low-pressure arc discharge, a study was made of the spatiotemporal stability of a pulsed-periodic beam of a large cross section (750×150) mm2, outputted into the atmosphere through an outlet foil window. The research was carried out using an automated system that allows real-time measurements with the ability to visualize the data on the computer. This system allows to ensure the accuracy of measurements no worse than ±2% and differs from the known analogues in compactness, reliability and simplicity of design. The use of this system made it possible to investigate the distribution of the current density over the beam cross-section in a wide range of its parameters, such as beam energy, beam current, and beam current pulse duration. A satisfactory agreement between past and present experimental data is shown. The use of this system for measuring the current density distribution along the beam cross section makes it possible to substantially increase the accuracy of the design of the scientific experiment, and, consequently, the speed of debugging and the repeatability of the technological process.

The method for the electron beam cross section measurement based on the detection of Cherenkov radiation in dielectric fiber

The article describes a method to measure the electron beam cross section. This method is based on the registration of Cherenkov radiation intensity generated in a dielectric fiber during the interaction with fast electrons. A section of fiber optic cable serves as a detecting unit. The fiber is placed parallel to the direction, in which the electron beam propagates. The spatial distribution of the beam intensity is measured by means of the line-by-line fiber scanning of the beam in the plane being measured. Light photons are generated in the fiber and propagate along it, reaching the photomultiplier, which is used to record the photon intensity. The quantity of the electrons caught in the fiber is in direct proportion to the Cherenkov radiation intensity. This makes it possible to measure the beam cross section by the dependence of the photomultiplier output signal on the fiber location. Finally, the article describes a proof-of-principle experiment for this method carried out for a 5.7 MeV microtron electron beam and the obtained results.

Generation, transport, and efficient extraction of a large cross-section electron beam into an air in an accelerator with a mesh plasma cathode

AbstractThe paper presents experimental and theoretical research data on the generation, transport, and extraction of a large cross-section (750 × 150 mm2) electron beam into the air through a thin metal foil in an accelerator with a mesh plasma cathode on the bases of a low-pressure arc and with a multi-aperture two-electrode electron-optical system. When the burning conditions of the arc discharge, responsible for the generation of the emission plasma, is changed, the characteristics of this plasma were investigated, including under the conditions of the selection of electrons from it. Our experiments show that at an accelerating voltage of 200 kV, current in the accelerating gap of up to 30 A, and full width at half maximum of up to 100 µm, the average extracted power is ≈4 kW and the extracted beam current is ≈85% from the common current into the accelerating gap. Our numerical estimates give a good correlation between the arc and emission plasma parameters depending on the electrode configuration in the discharge system and on the mechanism of electron beam generation. Analysis of the emission plasma parameters under different arc conditions and of the mechanisms responsible for the beam energy loss suggests that most of the energy in the accelerator is lost at the support grid and at the output foil due to defocusing of the beam and partial electron reflection from the foil. Other mechanisms that decrease the extracted beam energy are discussed.

The Role of Phase Changes in TiO2/Pt/TiO2 Filaments

This work analyses the role of phase changes in TiO2/Pt/TiO2 layer stacks for micro-heater application regarding their stability and reliable operation. The polycrystalline Pt layer wrapped in a TiO2 adhesion layer underwent a continuous recrystallisation in a self-heating operation causing a drift in the resistance (R) versus temperature (T) performance. Simultaneously, the TiO2 adhesion layer also deteriorates at high temperature by phase changes from amorphous to anatase and rutile crystallite formation, which not only influences the Pt diffusion in different migration phenomena, but also reduces the cross section of the Pt heater wire. Thorough scanning electron microscopy, energy dispersive spectroscopy, cross-sectional transmission electron microscopy (XTEM) and electron beam diffraction analysis of the structures operated at increasing temperature revealed the elemental structural processes leading to the instabilities and the accelerated degradation, resulting in rapid breakdown of the heater wire. Owing to stability and reliability criteria, the conditions for safe operation of these layer structures could be determined.

Методика автоматизированного измерения пространственных распределений плотности тока технологических электронных пучков

The importance of developing an automated technique for measuring spatial current density distributions of process electron beams is shown. It has been proven that immediate methods based on directly measuring the electron beam current components are of the main interest for constructing monitoring and control systems in electron beam-based process installations, because it is only these methods that can provide reliable information about the spatial distribution of current density. Experimental investigations of spatial current density distributions for electron beams with power capacities up to 6 kW have been carried out. The distributions obtained by the probe method are analyzed, and their deviations from the normal distribution function and axial symmetry are revealed. The limitations of the probe method based on the heat flux density and beam power are determined, and an express method for measuring the current density radial distribution over the electron beam cross section is proposed, which is based on using the direct edge method and on numerically processing the time dependences of the current. A scheme for quantifying the radial distribution of the electron beam current density is given. The possibility of applying the proposed technique for measuring the characteristics of beams with a power density up to 1.8∙104 W/cm2 using a copper collector has been experimentally confirmed. It is shown that the developed technique is necessary for mathematically reconstructing the current density volume distribution using the basic principles of electronic optics.

A Wideband Microfabricated Ka-Band Planar Helix Slow-Wave Structure

A Ka-band planar helix slow-wave structure (SWS) which is suitable for microfabrication is proposed and its design is described in this paper. A wideband design is achieved by using dispersion control techniques. The design shows an $S_{11}$ better than −20 dB over a 42.8% cold-test bandwidth with discrete input and output ports. Cold-test results for coplanar waveguide ports are also presented. The hot-test parameters of the SWS with discrete ports are investigated using CST Particle Studio. For an elliptical cross-sectional electron beam with the beam voltage of 3.72 kV and the current of 50 mA, a 3-dB small-signal gain bandwidth of 48.5% and a maximum gain of 42 dB are achieved. Saturated power of 26.5 W is achieved by using pitch tapering. Hot-test performance of the proposed SWS including a sever for high gain applications is also presented. Thermal simulations using CST have been carried out showing that the proposed SWS can have very good thermal dissipation properties. RF electric field values at some critical locations in the SWS have also been examined from the point of view of dielectric breakdown.

Investigation of the stability of the electron source with a multi-aperture plasma emitter generating a large cross-section electron beam

An experiment was performed to investigate the electric strength of the high-voltage acceleration gap of an electron source with a multi-aperture plasma emitter generating a beam of large cross section (750 × 150 mm2) extracted into the atmosphere through a thin metal foil. It has been shown that the use of a mask in the plasma emitter which partitions the overall emission region to produce a plurality of small-cross-section beamlets, so that the extracted beam is a superposition of beamlets formed by individual emission units whose plasma boundary is stabilized by a fine metal grid, increases the electric strength of the high-voltage acceleration gap. This is of critical importance in cases where the electron source is operated in a repetitive pulse mode at high average power of the beam. In addition, an increase in the electric strength of the acceleration gap is promoted by that the modernized cathode assemblies of the plasma emitter are arranged normal to the axis along which electrons are extracted into the acceleration gap.

<inline-formula> <tex-math notation="TeX">\(X\) </tex-math></inline-formula>-Band Relativistic Cherenkov Microwave Oscillator With Increased Cross-Sectional Electron Beam

Based on numerical simulation, a scheme of the \(X\) -band relativistic Cherenkov microwave oscillator with a hollow cylindrical increased cross-sectional electron beam transported by the external magnetic field is considered. For the electron energy of \(\sim 0.5\) MeV and electron beamwidth of \(\sim 5\) mm, an effective 100-ns-long pulse mode in a reduced magnetic field of 0.75 T has been calculated. Within the stationary stage of oscillation, the maximum simulated microwave power for the operating TM01 mode was 630 MW that corresponded to the oscillator efficiency of 34% at the oscillation frequency of 10 GHz.

Generation of a large cross-section electron beam in the vacuum diode with rod current returns

AbstractThe results of the experimental studies of the high-power e-beam accelerator producing six radially convergent electron beams are presented. The studies are aimed to increase the energy of the electron beam transported through the foil into the gas-filled chamber by using the rod-shaped current returns in the diode at small inter-electrode gaps. Installation of these rod current returns shields the periphery regions of the diode from the current field in the central part thus reducing the field at the diode edge. The inter-electrode distance, the shape, and the sizes of the cathodes are chosen by taking into account the magnetic field reduction in the diode. It is shown that in such type of the diode the electrons impact the foil almost normally to its surface, and the electron beams enter the output windows completely. Such type of the diode allows increasing the efficiency of the electron beam energy transfer into the gas by 30%.

Indications of short minority-carrier lifetime in kesterite solar cells

Solar cells based on kesterite absorbers consistently show lower voltages than those based on chalcopyrites with the same bandgap. We use three different experimental methods and associated data analysis to determine minority-carrier lifetime in a 9.4%-efficient Cu2ZnSnSe4 device. The methods are cross-sectional electron-beam induced current, quantum efficiency, and time-resolved photoluminescence. These methods independently indicate minority-carrier lifetimes of a few nanoseconds. A comparison of current-voltage measurements and device modeling suggests that these short minority-carrier lifetimes cause a significant limitation on the voltage produced by the device. The comparison also implies that low minority-carrier lifetime alone does not account for all voltage loss in these devices.

Electronic and structural properties of femtosecond laser sulfur hyperdoped silicon pn-junctions

The structural properties of femtosecond laser sulfur hyperdoped silicon pn-junctions are correlated to electronic transport characteristics at the interface. The depth of the planar space charge region obtained from cross-sectional electron beam induced current analysis is in good agreement with the sulfur concentration depth profile, derived from secondary ion mass spectroscopy. EBIC signals from the crest regions of the laser structured surface reveal increased recombination activity. Using transmission electron microscopy, we show that such recombination is related to dislocations, which are most probably highly decorated with sulfur.

Application of rod return-current conductors for decreasing the magnetic field of the vacuum diode

Results of the physical simulation and numerical calculations of magnetic field of the high-power vacuum diode with a large electron-beam cross section in the absence and with diode-installed return-current conductors in the form of rods are given. It is shown that the use of rods decreases the magnetic induction at the edge of the beam, while the field in the central part of the diode increases. It is found that the distribution of the magnetic field in the interelectrode cathode-anode gap in the presence of rods depends on the gap length between the back side of the cathode and the walls of the vacuum chamber. The location of the rods that halves the induction of the magnetic field at the edge of the cathode with the reasonable induction increase in the central part is found.

Direct observation of minority carrier lifetime improvement in InAs/GaSb type-II superlattice photodiodes via interfacial layer control

We present improved performance in strain-balanced InAs/GaSb type-II superlattice photodetectors grown using InSb interfacial layers, measured using a cross-sectional electron beam induced current (EBIC) technique to obtain minority carrier diffusion characteristics. We detail a modified EBIC model that accounts for the long absorber regions in photodetectors and fit the experimental data. We find a significant increase in the minority hole lifetime (up to 157 ns) and increased minority electron lifetime due to the interfacial layers. Additionally, electrical characterization of the device temperature-dependent resistance-area product reveals that the interfacial treatment improves the device dark current at lower temperatures.

A large-area continuous accelerator with the extraction of a high-density electron beam

The design features of the electron accelerator with a large-area 200-keV beam and results of its investigation are described. The accelerator is based on a set of discrete longitudinal filament cathodes and operates in the continuous mode. The cross section of the beam extracted into the atmosphere is 40 × 50 cm2, and the maximal current density of the extracted electron beam is up to 100 μA/cm2. The nonuniformity of the current density distribution over the electron beam cross section is 10% or less.

Thermal imaging diagnostics of high-current electron beams

The thermal imaging diagnostics of measuring pulsed electron beam energy density is presented. It provides control of the electron energy spectrum and a measure of the density distribution of the electron beam cross section, the spatial distribution of electrons with energies in the selected range, and the total energy of the electron beam. The diagnostics is based on the thermal imager registration of the imaging electron beam thermal print in a material with low bulk density and low thermal conductivity. Testing of the thermal imaging diagnostics has been conducted on a pulsed electron accelerator TEU-500. The energy of the electrons was 300-500 keV, the density of the electron current was 0.1-0.4 kA/cm(2), the duration of the pulse (at half-height) was 60 ns, and the energy in the pulse was up to 100 J. To register the thermal print, a thermal imager Fluke-Ti10 was used. Testing showed that the sensitivity of a typical thermal imager provides the registration of a pulsed electron beam heat pattern within one pulse with energy density over 0.1 J/cm(2) (or with current density over 10 A/cm(2), pulse duration of 60 ns and electron energy of 400 keV) with the spatial resolution of 0.9-1 mm. In contrast to the method of using radiosensitive (dosimetric) materials, thermal imaging diagnostics does not require either expensive consumables, or plenty of processing time.

Production of Nanopowders Using Nanosecond Electron Beam

Frequency nanosecond electron accelerators type URT has been developed for use in radiation technologies. The accelerator includes a thyratron, a pulse transformer and a semiconductor opening switch. The accelerating voltage is up to 0.9 MV, FWHM pulse length is up to 60 ns, and the repetition rate is up to 250 Hz. A metal ceramic cathode, which is used in the accelerator, provides an electron beam cross section up to 16 cm in diameter or rectangular with the dimensions of 45 * 5cm2 at a maximum density of the pulse current equal to 2 A/cm2. Thus, a family of nanosecond electron accelerators has been developed for use in radiation technologies applied to layers up to 0.4 g/cm2 thick, such as production of nanopowders from gas and liquid precursors. Experiments on the irradiation of silver nitrate solutions in various liquids by a URT-0.5 accelerator facilitated the development of technology for producing silver nanopowders (NPs). The powder yield and particle size as a function of the irradiation mode has been established. An increase in the adsorbed dose results in an increased powder yield; however, the particle size decreases and the powder agglomeration rate increases. Therefore, the targeted production of silver NPs with a mean particle size in the range of 90–1100 nm is possible. Besides to produce TiO2 and SiO2 NPs the gas precursors were used.

Development of High Power Electron Beam Measuring and Analyzing System for Microwave Vacuum Electron Devices

Abstract The measurement and analysis of high power electron beam during its formation and transmission are the basic scientific problems and key techniques for the development of high performance microwave vacuum electron devices, which are widely used in the fields of military weapon, microwave system and scientific instruments. In this paper, the dynamic parameters measurement and analysis system being built in Institute of Electronics, Chinese Academy of Sciences (IECAS) recently are introduced. The instrument are designed to determine the cross-section, the current density, and the energy resolution of the high power electron beam during its formation and transmission process, which are available both for the electron gun and the electron optics system respectively. Then the three dimension trajectory images of the electron beam can be rebuilt and display with computer controlled data acquisition and processing system easily. Thus, much more complicated structures are considered and solved completely to achieve its detection and analysis, such as big chamber with 10-6 Pa high vacuum system, the controlled detector movement system in axis direction with distance of 600 mm inside the vacuum chamber, the electron beam energy analysis system with high resolution of 0.5%, and the electron beam cross-section and density detector using the YAG: Ce crystal and CCD imaging system et al. At present, the key parts of the instrument have been finished, the cross-section experiment of the electron beam have been performed successfully. Hereafter, the instrument will be used to measure and analyze the electron beam with the electron gun and electron optics system for the single beam and multiple beam klystron, gyrotron, sheet beam device, and traveling wave tube etc. thoroughly.