Electron Beam Evaporation Research Articles

Reduction of absorption of Ta2O5 monolayers through the suppression of structural defects by employing an appropriate ionic oxygen concentration

Ultralow-absorption laser films have critical applications in high-power continuous-laser and gravitational-wave-detection systems. During film deposition, the ionic oxygen concentration significantly affects the absorption loss of the film. In this study, Ta2O5 monolayers were deposited using an ion-assisted electron beam evaporation technique, and the weak absorption at 1064 nm, temperature rise, optical band gap, element content, and binding energy were tested and analyzed. The band structure and microdefects of the Ta2O5 films were characterized, and their correlation with the absorption properties was established. The analyses revealed that the primary mechanism responsible for reducing the absorption loss in Ta2O5 films was an appropriate ionic oxygen concentration, which improved the optical band gap and stoichiometric ratio and reduced oxygen vacancy defects. For Ta2O5 monolayers deposited with the optimal ionic oxygen concentration, the weak absorption was approximately 7.2 ppm and the temperature rise was approximately 0.6 °C, 1/4 and 1/3 of the values of those deposited with an excessive concentration, respectively—an important finding in the preparation of ultralow-absorption laser films.

Structural and optical studies of Sb2S3 films deposited by electron beam evaporation with post-annealing treatment

Structural and optical studies of Sb2S3 films deposited by electron beam evaporation with post-annealing treatment

Ion composition of beam plasma formed by electron beam evaporation of YSZ ceramic in medium vacuum

Ion composition of beam plasma formed by electron beam evaporation of YSZ ceramic in medium vacuum

Fabrication of birefringent plasmonic structures using novel collimated glancing angle E-beam evaporation method

Fabrication of birefringent plasmonic structures using novel collimated glancing angle E-beam evaporation method

Nanostructured zinc doped tungsten oxide films for antibacterial applications

Pure and zinc doped tungsten oxide films were deposited on glass substrates at various wt% of zinc by using the electron beam evaporation method. The scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis-NIR double beam spectrometry techniques were used to assess the properties of pure and zinc doped tungsten oxide films. From the SEM results, undoped tungsten oxide films exhibited a rice hull type nanostructure. The zinc doped tungsten oxide films exhibited a spider net structure. The antibacterial activity of Zn-WO3 films was studied with Pseudomonas aeruginosa. The zinc doped WO3 films are effectively inhibiting the bacteria’s growth.

Failure Mechanism Analysis of Thermal Barrier Coatings Under a Service Simulation Environment

In this paper, the ceramic coating of thermal barrier coatings (TBCs) was prepared on the surface of the tube specimens by Electron Beam Physical Vapor Deposition (EB-PVD) process. Subsequently, a service simulation was conducted using a simulation device to analyze the failure behavior of the TBCs. The effects of high-temperature sintering and CaO-MgO-Al2O3-SiO2 (CMAS) corrosion on the microstructural evolution, phase structural changes, and insulation performance of the thermal barrier coatings were investigated. The results indicated that with increasing high-temperature sintering time, the “feather” structures at the boundaries of the columnar grains evolve into the “tentacle” structure that facilitates the fusion of adjacent columnar grains, resulting in increased grain diameter and wider gaps. No transformation from t’-ZrO2 to the monoclinic phase m-ZrO2 occurred during the high-temperature sintering process. Over time, CMAS wets the coating surface and infiltrates the interior of the coating, causing corrosion to the Yttria-stabilised zirconia (YSZ) and accelerating sintering. A new phase, ZrSiO4, was formed after corrosion without inducing the transition.

Origin of the formation of isostructural bcc-Fe+bcc-Cu nanocomposites in Fe–Cu alloy via vacuum co-deposition

This study examined the influence of substrate temperature and the ratio of iron and copper vapor flow on the structural state of Fe–Cu vacuum condensates. XRD patterns of the condensates deposited under specific electron beam physical vapor deposition process parameters revealed peaks corresponding to either bcc or bcc+fcc phases. Analysis of the lattice parameter of the single bcc structure indicates that only a portion of the copper atoms dissolve in the bcc-Fe lattice, while undissolved copper atoms form bcc-Cu inclusions that are coherent with the bcc-Fe lattice. A model for the formation of the bcc-Cu structure as an adaptive phase is proposed. The formation of the adaptive phase in vacuum condensates is driven by the bcc-Cu epitaxy on the surface of bcc-Fe crystallites and excess vacancies in the condensate structure. As the copper concentration in the isostructural Fe–Cu composite increases, the level of microstrain in its bcc crystal lattice also increases. The transformation of bcc-Cu particles into fcc-Cu via a shear mechanism occurs when heated above 400 °C. It was found that increasing the deposition temperature reduces the concentration range for the formation of the isostructural composite. It is suggested that higher deposition temperatures and increased copper concentration lead to larger copper particle sizes and reduced excess vacancy concentration, which disrupts their coherence with the bcc-Fe matrix. As a result, a composite with a eutectic-like microstructure consisting of bcc-Fe and fcc-Cu phases forms directly during vapor phase condensation.

Unlocking the Performance of Next-generation Non-volatile Capacitive Memory Devices with Ti-doped ZnO Nano Wires via Pulsed Laser Deposition

This paper investigates the impact of titanium (Ti) doping on zinc oxide (ZnO) nano wires (NWs) in non-volatile capacitive memory devices (NVCMDs) through fabrication and characterizations. ZnO NWs were fabricated using pulsed laser deposition (PLD), while Ti thin film (TF) was deposited via electron beam evaporation (e-beam). Field emission gun scanning electron microscopy (FEGSEM) confirmed the formation of ZnO NWs and Ti-doped ZnO NWs (Ti:ZnO NWs) on an n-type silicon (Si) substrates, with elemental compositions determined by energy dispersive X-ray spectroscopy (EDX). Structural characterization was conducted on the samples using high-resolution X-ray diffraction (HRXRD). Gold (Au) interdigitated electrodes (IDE) were employed to fabricate two distinct devices: Au IDE/ZnO NWs and Au IDE/Ti:ZnO NWs. Comparative analysis revealed that the Au IDE/Ti:ZnO NWs device exhibited a lower frequency dispersion fd value (0.025×109 F) compared to Au IDE/ZnO NWs device (0.029×109 F), indicating enhanced signal propagation due to Ti doping. The Au IDE/Ti:ZnO NWs device also demonstrated a high free charge carrier donor concentration ND value of 2.02×1012 /cm3, a significant trap concentration Nt value of 4.44×1011 /cm3 at an 8MHz frequency response. Additionally, it exhibited lower tangent loss (tan(δ)) value of 7430, maximum conductance Gmmax value of 13.40 mS, lower interface trap state density (ITSD) value of 2.05×1014 eV1 cm2, a maximum memory window (∆VMW) of 6.9V at ±15V, improved endurance, and superior data retention, making the Au IDE/Ti:ZnO NWs device a promising candidate for next-generation NVCMDs applications.

ELECTRON BEAM EVAPORATION OF SILICON CARBIDE TO PRODUCE SILICON-CARBON COATINGS

In this paper, we describe our work on the formation of silicon-carbon (Si-C) coatings by electron beam evaporation of a silicon carbide target in a medium vacuum using a forevacuum-pressure plasma-cathode electron source. The films obtained were characterized, which showed that the properties of the Si-C coatings were similar to those prepared by plasma-chemical methods.

Infrequent trigonal crystal system CoNb thin films: investigation of growth behavior, microstructure and magnetic properties

Magnetic films with excellent initial permeability, high resonance frequency, suitable anisotropy fields, and well compatibility are highly desirable for on-chip inductors and transformers. Here, Co90Nb10 thin films with different thicknesses are grown on Si substrates of different orientations using an electron beam evaporation technique. A rare trigonal crystal structure of the CoNb films was observed and was virtually unaffected by substrate orientation. Films grown exhibit thickness-dependent magnetic behavior: coercivity initially decreases and then increases, while the in-plane anisotropy field progressively diminishes. Meanwhile, the initial permeability increases initially before decreasing, and the resonance frequency continuously decreases as the thickness increases. The resultant Co90Nb10/Si (111)-50 nm film displays a high μi of 496 and a great fr of 2.1GHz. The improved magnetic performance originates from the smaller crystallite size, smoother surface roughness, and suitable in-plane anisotropy field. Moreover, the in-plane anisotropy transition to the out-of-plane anisotropy in the Co90Nb10 films whose thickness exceeds 70nm, which is attributed to the growth of the coarse columnar grains once the critical thickness is exceeded. This study demonstrates the correlation between the growth behavior, microstructure, and magnetic properties of CoNb thin films, presenting a new potential for utilizing Co-based thin films in high-frequency applications.

Electron-beam-evaporated NiOX for efficient and stable semi-transparent perovskite solar cells and modules

Herein, thermally stable ST-PSCs have been fabricated by using vacuum deposited CsPbBr3 perovskite and electron-beam evaporation deposited NiOX. Furthermore, we achieved a champion efficiency of 5.5% for 5 cm × 5 cm mini-modules with an AVT of 49.1%.

Heterostructure growth, electrical transport and electronic structure of crystalline Dirac nodal arc semimetal PtSn4

Topological semimetals have recently garnered widespread interest in the quantum materials research community due to their symmetry-protected surface states with dissipationless transport which have potential applications in next-generation low-power electronic devices. One such material, , exhibits Dirac nodal arcs and although the topological properties of single crystals have been investigated, there have been no reports in crystalline thin film geometry. We examined the growth of heterostructures on a range of single crystals by optimizing the electron beam evaporation of Pt and Sn and studied the effect of vacuum thermal annealing on phase and crystallinity. The electrical resistivity was fitted to a modified Bloch–Grüneisen model with a residual resistivity of 79.43(1) cm at 2K and a Debye temperature of 200K. Nonlinear Hall resistance indicated the presence of more than one carrier type with an effective carrier mobility of 33.6 and concentration of 1.41 at 300 K. X-ray photoemission spectra were in close agreement with convolved density of states and a work function of 4.7(2) eV was determined for the (010) surface. This study will facilitate measurements that require heterostructure geometry, such as spin and topological Hall effect, and will facilitate potential device incorporation in future quantum technologies.

Surface Characteristics and Performance Optimization of W-Doped Vanadium Dioxide Thin Films

This study explores the surface characteristics evaluation and performance optimization of tungsten (W)-doped vanadium dioxide (VO2) thin films. W-doped vanadium dioxide films were deposited on B270 glass substrates using an electron beam evaporation technique combined with the ion beam-assisted deposition (IAD) method. The Taguchi method was used to analyze the performance optimization of VO2 thin films, and L16 orthogonal array design and Minitab software were used for optimization calculations. The surface roughness, visible light transmittance, infrared transmittance, and residual stress of un-doped and tungsten-doped (3–5%) VO2 thin films are set as the quality performance indicators of thin films. The goal is to identify the key factors that affect the performance of VO2 thin films during deposition and optimize their process parameters. The experimental results showed that a VO2 thin film with 3% tungsten doping, an oxygen flow rate of 60 sccm, a heating temperature of 280 °C, and a film thickness of 60 nm exhibited the lowest surface roughness of 2.12 nm. A VO2 thin film with 5% tungsten doping, an oxygen flow rate of 0 sccm, a heating temperature of 280 °C, and a film thickness of 60 nm had the highest visible light transmittance at 64.33%. When the oxygen flow rate was 60 sccm, the heating temperature was 295 °C, the film thickness was 150 nm, and the tungsten doping was 5%, the VO2 thin film showed the lowest infrared transmittance of 31.34%. A thin film with 5% tungsten doping, an oxygen flow rate of 20 sccm, a heating temperature of 265 °C, and a film thickness of 120 nm exhibited the lowest residual stress of −0.195 GPa.

Improvement of Photocatalytic and Photodegradable ZnSe Nanorods by a Vulcanization Strategy.

Photocatalysts composed of ZnSe nanorods were prepared by using a glancing angle deposition technique facilitated by electron beam evaporation equipment. To enhance the photocatalytic efficiency of ZnSe, a vulcanization process was introduced. The impact of various parameters, including curing temperature, duration, and nanorod length, on the photocatalytic performance was systematically examined. Comprehensive analysis using X-ray diffraction, scanning electron microscopy, and photocurrent density-potential curves identified optimal vulcanization conditions at 300 °C for 45 min for 170 nm ZnSe nanorods. Under these conditions, the photocurrent reached 44.53 μA/cm2, approximately 7-fold greater than that of untreated ZnSe nanorods. Furthermore, the degradation efficiency of Rhodamine B increased by 50%. Detailed analysis of the photocatalytic mechanism revealed that sulfurization not only enhances light absorption but also facilitates the separation of photogenerated carriers through the formation of ZnS.

Growth and Characterization of NiO Thin Films for Selective Detection of Formaldehyde Vapor

The formation of nickel oxide (NiO) nanostructures using controlled thermal oxidation of thin nickel (Ni) films and their successive use as gas‐sensing materials for selective detection of low‐concentration formaldehyde vapor are discussed here. High‐purity Ni were deposited on glass/quartz substrates using a vacuum assisted electron beam (E‐beam) evaporation technique. Afterwards, thermal oxidation of these Ni thin films was conducted at various temperatures in air ambient condition. Different surface characterization techniques are employed to investigate the structure, chemistry, and electronic properties of these as‐grown oxide nanostructures. X‐ray diffraction analysis revealed that the thermal oxidation starts above 400 °C. Presence of metallic nickel peak even after oxidation at 500 °C for 5 h confirms its oxidation resistance. Increase in oxidation temperature improves the crystalline quality. Scanning electron microscopy imaging depicts an increase in particle size with oxidation temperature and a highly porous surface morphology above 800 °C. Raman spectroscopy identified the characteristic modes of NiO. UV‐Visible data exhibits a redshift in optical bandgap whereas X‐ray photoemission spectroscopy analysis reveals a gradual increase in oxygen content within the oxide layer. Finally, these NiO films show a high sensitivity and selectivity toward formaldehyde vapor sensing against a few other volatile organic compounds.

Effect of physical vapor deposition on contacts to 2D MoS2

Two-dimensional (2D) molybdenum disulfide (MoS2) holds immense promise for next-generation electronic applications. However, the role of contact deposition at the metal/semiconductor interface remains a critical factor influencing device performance. This study investigates the impact of different metal deposition techniques, specifically electron-beam evaporation and sputtering, for depositing Cu, Pd, Bi, Sn, Pt, and In. Utilizing Raman spectroscopy with backside illumination, we observe changes at the buried metal/1L MoS2 interface after metal deposition. Sputter deposition causes more damage to monolayer MoS2 than electron-beam evaporation, as indicated by partial or complete disappearance of first-order E′(Γ)α and A′1(Γ)α Raman modes post-deposition. We correlated the degree of damage from sputtered atoms to the cohesive energies of the sputtered material. Through fabrication and testing of field-effect transistors, we demonstrate that electron-beam evaporated Sn/Au contacts exhibit superior performance including reduced contact resistance (~12×), enhanced mobility (~4.3×), and lower subthreshold slope (~0.6×) compared to their sputtered counterparts. Our findings underscore the importance of contact fabrication methods for optimizing the performance of 2D MoS2 devices and the value of Raman spectroscopy with backside illumination for gaining insight into contact performance.

Compact 2 × 2 silicon thermo-optic switch with P π of ∼ 1.4 mW and extinction ratio > 28 dB over C-band

We have designed and experimentally demonstrated a compact 2 × 2 silicon thermo-optic Mach-Zehnder switch with a Pπ of ∼ 1.4 mW and an extinction ratio of > 28 dB over C-band. We use spiral configurations for both the silicon waveguide and the metal heater in the phase shifters to improve thermal efficiency. The densely packed silicon waveguides are connected by hybrid Euler bends. The adjacent straight waveguides have different widths of 400 nm and 550 nm to achieve isolation between the optical fields. We present simulation results of the hybrid Euler bends and the thermal field distribution. The device is fabricated by e-beam lithography, dry etching, and e-beam evaporation, resulting in a device footprint of ∼ 0.24 × 0.36 mm2, with each phase shifter occupying ∼ 0.11 × 0.11 mm2. The measured Pπ of ∼ 1.4 mW is in agreement with the simulations. The extinction ratio is > 28 dB over the C-band due to the highly balanced 2 × 2 multimode interferometer (MMI) coupler used. This device is well suited for the construction of large-scale photonic integrated circuits (PICs) for applications requiring a large number of 2 × 2 optical switches with low crosstalk and low power consumption, such as optical beamforming networks (OBFNs) for microwave beamforming and optical phased arrays (OPAs) for optical beamforming.

Analysis of air and vacuum annealing on microstructural, optical and electrical characteristics of In2O3 layers for gas sensors

Abstract With consideration of significant potential of metal oxides in the effective gas sensing applications, herein, an assessment of air and vacuum annealing to the physical characteristics of In2O3 (Indium Oxide) layers is meticulously unveiled. Development of 550 nm thin In2O3 films on glass and ITO (Indium doped Tin oxide) coated substrates is accomplished by means of electron beam evaporation technique. An annealing treatment on grown In2O3 layers is executed at 300 °C, 375 °C and 450 °C for one hour in air and vacuum conditions followed by their subsequent characterizations using X-ray diffractometer, UV-Vis spectrophotometer, source meter, scanning electron microscope, and energy dispersive spectroscope tools. The crystallite size corresponding to predominant cubic peak (222) is obtained in 23-33 nm range for both types of films and observed least at 450 °C. Optical analysis exhibited that In2O3 films showed maximum transmittance of ~90% in visible region whereas band gap is measured within the range 2.20-3.50 eV. The electrical measurements unveiled Ohmic nature of films contacts where resistivity of In2O3 layers is found to be enhanced with air and vacuum annealing temperature. The morphological micrographs indicate uniform In2O3 films deposition with nanospherical grains and EDS patterns exhibited In and O peaks ensuring successful deposition of n-type In2O3 films with In richness and O vacancies. The gas sensor fabricated by using In2O3 films annealed in air at 450 °C is assessed for detection of H2S gas which showed gas response and response time of 1.08 and 38 seconds, respectively.

Electron-Beam-Evaporated Nickel Oxide Thin Films for Application as a Hole Transport Layer in Photovoltaics

We present the growth of nickel oxide (NiO) thin films as a hole transport material in photovoltaic devices using the e-beam evaporation technique. The metal oxide layers were reactively deposited at a substrate temperature of 200 °C using an electron beam evaporator under an oxygen atmosphere. The oxide films reactively grown through electron-beam evaporation were optimized for carrier transport layers. Optical and structural characterizations were performed using ultraviolet–visible (UV–Vis) spectrometry, X-ray diffraction, contact angle measurements, scanning electron microscopy, and Hall effect measurements. The study of these films confirmed that the NiO layer is a suitable candidate for use as a hole transport layer based on Hall effect measurements. A morphological study using field-emission scanning electron microscopy confirmed the growth of compact, uniform, and defect-free metal oxide layers. Contact angle measurements revealed that the films possessed semi-hydrophilic properties, contributing to improved stability by repelling water from their surfaces. The stoichiometry of the films was influenced by the oxygen pressure during deposition, which affected both their morphological and optical features. The NiO films exhibited a transmittance exceeding 80% in the visible spectrum. These findings highlight the potential applications of such nickel oxide films as hole transport material layers.

CMAS corrosion behavior of interface for EB-PVD Gd2Zr2O7/YSZ thermal barrier coatings

Thermal barrier coatings (TBCs) of aero-engine surfaces are facing complex working conditions such as high-temperature oxidation, hot-cold cycling, and CMAS corrosion. Gd2Zr2O7 (GZO)/YSZ bilayer ceramic TBCs are one of the coating systems that have been applied in aero-engine TBCs. One of the failure problems faced by the columnar crystalline bilayer GZO/YSZ TBCs prepared by electron beam-physical vapor deposition (EB-PVD) technology in high-temperature environments is the CMAS high-temperature corrosion problem. In this study, CMAS corrosion tests of GZO/YSZ bilayer structure TBCs were conducted at 1200 °C for 1h, 2h and 4h, respectively. The focus was on exploring the corrosion characteristics and mechanisms of the coating interface and surface after high-temperature corrosion. It was found that CMAS corrosion was dominated at the coating interface, accompanied by coating sintering, resulting in coating spalling at the interface. The coating interface was also analyzed by TEM after 4h corrosion, and it was found that an apatite phase was formed at the GZO/YSZ interface, which was embedded in the lattice of YSZ. Finally, the corrosion failure mechanism of the GZO/YSZ bilayer structure TBCs was proposed by the above CMAS high-temperature corrosion test.