Electron Beam Evaporation Research Articles

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.

Magnetoresistance Behavior of Silver‐Doped Zinc Oxide Films

Silver (0.24 at%) doped zinc oxide (AgZnO) films are deposited on glass substrates using electron beam evaporation. The resistance is measured in the temperature range of 4–380 K under magnetic fields (H ) of 0.1 and 0.25 T. In the low‐temperature range, the resistance of the annealed AgZnO film exhibits peaks at 101, 130, and 160 K when H = 0 T. The peaks at 130 and 160 K disappear at H = 0.1 T, while the peak at 101 K exhibits positive magnetoresistance (MR) below 122 K and transitions to negative MR above 122 K at 0.25 T. At high temperatures, the resistance of the annealed AgZnO film follows the Arrhenius equation, with the activation energy increasing from 0.59 to 0.73 and 0.74 eV under H = 0.1 and 0.25 T, respectively, in the temperature ranges of 230–380 K and 230–320 K. In the low‐temperature range, the resistance is governed by Mott variable‐range hopping (VRH) model. A crossover from Mott to Efros–Shklovskii VRH mechanism is observed at different temperature ranges: 165–170 K, 145–165 K, and 135–165 K for H = 0, 0.1 and 0.25 T, respectively. Moreover, the Coulomb gap decreases, and the TM/TES ratio increases with the magnetic field, indicating changes in the electronic structure of the AgZnO film.

Investigation of traps in halide vapor-phase epitaxy-grown β-Ga2O3 epilayers/n+-Ga2O3 using deep-level transient spectroscopy

Abstract A detailed investigation of deep traps in halide vapor-phase epitaxy (HVPE)-grown β-Ga2O3 epilayers has been done by performing deep-level transient spectroscopy (DLTS) from 200 K to 500 K on Pt/β-Ga2O3 and Ni/β-Ga2O3 Schottky diodes. Similar results were obtained with a fill pulse width of 100 ms irrespective of the different Schottky metal contacts and epilayers. Two electron traps at E2 (E C–E T = 0.65 eV) and E3 (E C–E T = 0.68–0.70 eV) with effective capture cross-sections of 4.10 × 10−14 cm2 and 5.75 × 10−15 cm2 above 300 K were observed. Below 300 K, a deep trap with a negative DLTS signal peak was also observed at E1 (E C–E T = 0.34–0.35 eV) with a very low capture cross-section of 3.28 × 10−17 cm2. For a short pulse width of 100 μs, only two electron traps, E2 and E3, at energies of 0.72 eV and 0.73 eV were observed, and one order of higher corresponding effective capture cross-sections. All traps were found to be unaffected by the electric field during the field-dependent DLTS study. From the filling pulse width dependence DLTS study, a decrease in the capacitance transient amplitude with the increasing pulse width was observed opposite to the capture barrier kinetics of the traps and attributed to the emission of carriers during the capture process. Trap concentrations were found to be high at the interface using depth profiling DLTS. Based on the available literature, it is suggested that these traps are related to FeGa, Fe-related centers, and complexes with hydrogen or shallow donors, and might be affected or generated during metallization by the electron beam evaporator and chemical mechanical polishing.

Sn Penetrated Zincophilic Interface Design in Porous Zn Substrate for High Performance Zn-Ion Battery.

Rechargeable zinc-ion batteries are considered an ideal energy storage system due to their low cost and nonflammable aqueous electrolyte. However, dendrite growth, hydrogen evolution reaction, and self-corrosion of zinc anode brought about serious safety risks including short circuits and electrode expansion. Therefore, a modified host-design strategy with a 3D porous structure and bulk-phase penetrated zincophilic interface is proposed to boost the stability and lifetime of the Zn anode. The porous Zn substrate is constructed by universal HCl etching and the uniform and tight Sn-penetrated zincophilic interface is formed by effective electron beam evaporation (EBE). The porous substrate can uniform zinc ion flux and the Sn coating could effectively improve zinc ion deposition behavior, thus inhibiting the risk of dendrites growth and side reaction. As a result, the 3D Zn substrate with Sn interface (3D Zn@Sn) exhibits prolonged galvanostatic cycling performance up to 4500h with a low polarization of ≈25mV (1mAcm-2, 1mAhcm-2) in the symmetric cell. The full cell assembled with KVOH@Ti could maintain a high specific capacity of 148.6mAhg-1 after 500 galvanostatic cycles (10Ag-1). This work proposed an improved electrode design to realize the high performance of zinc ion batteries.

Failure behavior study of EB-PVD TBCs under CMAS corrosion and thermal shock cycles

Abstract Calcia-magnesia-alumino-silicate (CMAS) erosion has become a major obstacle, limiting the operating temperature and service life of Thermal barrier coatings (TBCs) in aircraft engines. Constructing simulation environments that replicate TBCs’ working conditions and exploring online, non-destructive detection techniques are reliable approaches to studying coatings’ failure, representing both a global research hotspot and a challenge in this field. The paper presents an initial endeavor to establish a simulation experiment for TBCs in aviation-engine within a CMAS environment. Experimental results show that electron beam physical vapor deposition (EB-PVD) Y2O3-stabilized ZrO2 (YSZ), one of the mainstream TBCs technologies, produced 20% surface spallation after 50 thermal-shock cycles under simulated CMAS corrosion conditions. Testing and analysis of the macroscopic and microscopic structures of the failed samples, combined with SEM, EDS, and XRD findings, revealed significant physical and chemical interactions between the ceramic layer and CMAS deposits, as well as phase transformation within the coatings, leading to substantial alterations in mechanical properties and ultimately causing the failure of EB-PVD YSZ.

Magneto-optical Kerr effect (MOKE) and magnetic force microscopy (MFM) studies on Cr/Ni nanodot arrays deposited using innovative nano-stencil method

AbstractNanodot arrays of Nickel (Ni) on Chromium (Cr), [Cr in two forms i. e. (Cr dot) and Cr (layer)] were fabricated by electron beam evaporation technique using nano-stencil. The deposition of a periodic dot pattern was confirmed through atomic force microscopy (AFM) imaging. The nano magnetic properties of the Cr/Ni nanodot arrays were probed using both Magnetic Force Microscopy (MFM) and Magneto-Optical Kerr Effect (MOKE) magnetometer. MOKE measurements unveiled saturated hysteresis with the exchange bias effect for the in-plane configuration and a minor hysteresis loop for the out-of-plane configuration in the Cr/Ni nanodot system. The experimental results were found to be in good agreement with the theoretical Stoner-Wohlfarth (SW) model. Additionally, the exchange bias effect was also observed in the Cr (thin film)/Ni (nanodot) system for both the in-plane and out-of-plane configurations, showing the dominating behavior of the Cr layer over the Ni dots due to its continuous layer and higher thickness. The observation of exchange bias properties was also verified through MFM measurements conducted with both positive and negative in-plane magnetic fields. Hence, this straightforward nano-stencil method holds significant promise for the streamlined production of patterned AFM/FM arrays enabling the comprehensive study of exchange bias phenomena. The magnetic properties of the Cr/Ni structure can be manipulated by depositing Cr either in nanodot form or in continuous layer form.

Development of Electron Beam Physical Vapor Deposition Coating Process for YSZ Material Using Domestic Equipment Technology

Development of Electron Beam Physical Vapor Deposition Coating Process for YSZ Material Using Domestic Equipment Technology

Atomic scale in-situ observation of gas-solid interaction regulating the pre-nucleation process of Pd atomic clusters

Advancements in nanotechnology have propelled the understanding of atomic-scale nucleation processes, essential for the evolution of atomic manufacturing. The process of amorphous precursors nucleation showcases a complex transition influenced by various factors. Utilizing aberration-corrected ETEM and theoretical calculation, we explore the nucleation of amorphous Pd atomic clusters. This study examines the nucleation dynamics and gas-solid interaction regulating of Pd clusters on ultrathin carbon films, prepared via electron beam evaporation. HRTEM observation and FFT analysis reveal that, in the early stage of nucleation, Pd cluster growth predominantly follows an Ostwald ripening-like mechanism. Atoms from smaller clusters migrate and attach to larger ones, facilitating their progression to critical nucleation size. Environmental conditions significantly influence this process; hydrogen atmospheres lower the surface energy of Pd clusters, reducing the critical nucleation size, while argon atmospheres impede growth of Pd clusters by occupying migration sites on the carbon surface. These insights into atomic cluster behavior and environmental interactions are crucial for understanding the early stages of nucleation from amorphous to crystalline and can help opens new avenues for the controlled fabrication of materials with optimized functionalities.

Exploration of High‐Pressure Annealing and Microwave Annealing in Palladium Germano‐Silicide Formation for Si0.8Ge0.2‐Based Complementary Metal‐Oxide–Semiconductor Transistors

In this study, forming palladium germano‐silicide on Si0.8Ge0.2‐based complementary metal‐oxide semiconductor (CMOS) transistors by high‐pressure annealing compared to microwave annealing is investigated. Boron‐doped Si0.8Ge0.2 layers are epitaxially grown on n‐type Si wafers, achieving an initial boron concentration of 5 × 1015 cm−3, which increase to ≈6 × 1020 cm−3 after microwave annealing, reducing sheet resistance. Palladium is deposited using electron beam evaporation to form a 15 nm layer on Si0.8Ge0.2 (200 nm)/Si (100) substrates. High‐pressure annealing is conducted from 300 to 500 °C in N2 ambiance at 5 kg cm−3, while microwave annealing is performed at 5.8 GHz and 1800–3000 W for 100 s. X‐ray diffractometer confirms high‐intensity Pd2Si phase formation, but scanning electron microscope and atomic force microscope reveal increased surface roughness and clustering after annealing. Sheet resistance increases from 10.35 Ω sq−1 (unannealed) to 131.8 Ω sq−1 (high‐pressure annealing at 300 °C) and 85.8 Ω sq−1 (microwave annealing at 1800 W). In these results, the trade‐offs between annealing methods and metal choices for achieving low contact resistance and Schottky barrier heights in p‐type Si0.8Ge0.2 CMOS circuits are highlighted.

The impact of proton ion irradiation on Se70Te20In10 thin films: Linear and non-linear optical properties for photonic applications

The examination of the linear and non-linear optical features was conducted on amorphous ternary Se70Te20 In10 thin films, which were exposed to proton irradiation energy of 3 MeV at varying fluences of 5×1013, 5×1014, 5×1015 and 5×1016 ions/cm2. The bulk sample was produced using the melt quenching method, and subsequently, thin films were obtained through electron beam evaporation. Calculations of linear and non-linear optical parameters were carried out based on transmittance and reflectance data acquired from UV–Vis–NIR spectroscopy spanning 300–2500 nm. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) confirmed an amorphous phase in the films. The optical parameters showed strong dependency on the proton radiation fluence. In addition, the existence of minima or maxima for a number of parameters at a fluence of 5×1014 ions/cm2 showed that this was the optimum fluence. The linear and non-linear properties showed that the sample have potential applications in photonic devices.

Experimental Performance Analysis of Fabricated Si/Ge Thin Film Structure

This paper is devoted to the evaluation of a Silicon/Germanium (Si/Ge) thin film structure based on experimental measurements. An electron beam evaporator was used to fabricatethis structure. The sample was prepared under high vacuum conditions (pressure of 10-5 Torr, power of 6 kV and current of 200 mA). At these conditions, it was possible to get films with thickness of approximately 300 Å. The capacitance–voltage (C–V) and current–voltage (I–V) measurements of the sample were performed by a staircase sweep of voltages from 0 to 5 V and back from 5 to 0 V at room temperature. The sample exhibits a low hysteresis in measurements; this hysteresis is gradually removed when the sample is exposed to temperatures until 80 °C using a Carbolite Oven. It is also observed that both C-V and I-V characteristic curves of the sample has been smoothened. This sample exhibits an electroforming behavior as a metal-oxide-semiconductor (MOS) device over a short time duration of the selected staircase double sweep, hence it can be exploited as a fast switching element in digital microelectronic circuits. In addition, the hysteresis changes over the range from room temperature until 80 °C have opened the door to the possibility of exploiting this sample as a proximity temperature sensor within that range of temperature.

Thermal cycling performance of GYbZ/YSZ thermal barrier coatings with different microstructures based on finite element simulation

Three (Gd0.9Yb0.1)2Zr2O7/YSZ double ceramic layer (DCL) thermal barrier coatings (TBCs) with different microstructures were manufactured by electron-beam physical vapor deposition (EB-PVD). The thermal cycling behavior of the three TBCs was evaluated comparatively at 1150 ℃. The results showed that TBCs with small columnar grains exhibited the best thermal cycling performance among all the tested TBCs. The effect of microstructure on thermal cycling behavior, including crack evolution and failure mode was discussed. A finite element model tailored to the microstructural characteristics of the DCL coatings was established. Several in-plane stress concentration points appeared in the taller GYbZ column due to discontinuities in strain tolerance resulting from sudden structural or compositional changes. Analysis of the strain energy release rate variation for each concentration point suggested that the predicted delamination position and process aligned with experimental results.

Synthesis of β-Ga2O3:Mg Thin Films by Electron Beam Evaporation and Postannealing

Doping divalent metal cations into Ga2O3 films plays a key role in adjusting the conductive behavior of the film. N-type high-resistivity β-Ga2O3:Mg films were prepared using electron beam evaporation and subsequent postannealing processing. Various characterization methods (X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence, etc.) revealed that the Mg content plays an important role in affecting the film quality. Specifically, when the Mg content in the film is 3.6%, the S2 film’s resistivity, carrier content, and carrier mobility are 59655.5 Ω·cm, 1.95 × 1014 cm3/C, and 0.53682 cm2/Vs. Also, the film exhibits a smoother surface, more refined grains, and higher self-trapped exciton emission efficiency. The Mg cation mainly substitutes the Ga+ cation at a tetrahedral site, acting as a trap for self-trapped holes.

Effect of pure (ligand-free) nanoparticles of magnetite in sodium chloride matrix on hematological indicators, blood gases, electrolytes and serum iron

AbstractOne of the physical methods for obtaining magnetite nanoparticles (NPs) is electron beam physical vapor deposition (EB PVD), which requires complex equipment, but allows obtaining a significant amount of pure (ligand-free) NPs. The biomedical application of such NPs is less studied than materials from other synthesis methods. The objective is to study the effect of pure magnetite NPs in the NaCl matrix obtained by EB PVD on hematological indicators, gases, electrolytes and parameters of iron metabolism in the blood of intact animals. The physical characteristics of NPs were studied using high-resolution transmission electron microscopy, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping, electron energy-loss spectroscopy, selected area electron diffraction and fast Fourier transform. In vivo experiments were conducted on albino male rats, which were injected with solution of magnetite-sodium chloride NPs (1.35 mg Fe/kg). After 3 and 72 h, hematological parameters, blood gases, electrolytes, and serum iron were determined. The synthesized NPs had an average size of 11 nm. They were identified as magnetite, where polycrystals and single crystals were present. The absence of contamination in crystal boundaries, clear orientation and orderliness of atoms in crystals were established. The administration of NPs in the sodium chloride matrix to animals was characterized by a transient increase in the main indicators of red blood accompanied by an increase in the saturation of erythrocytes with hemoglobin and their mean volume after 3 h. It did not worsen blood gases and pH, but decreased blood Na+ content after 72 h. The investigated NPs caused changes in the parameters of serum iron characteristic to iron preparations, which after 3 h were smaller compared to the reference iron drug, and after 72 h—similar to it. More intense rapid effects on hematological parameters at lower serum iron indicate greater activity of the studied pure magnetite NPs obtained by EB PVD syntesis compared to the reference iron preparation.

Influence of annealing on optical, morphological and electrophysical properties of granular silver nanostructures

The optical, morphological and electrophysical properties of silver nanostructures fabricated by electron beam evaporation and annealed at temperatures of 145 and 195 °C were studied. All samples are characterized by the presence of a pronounced surface plasmon absorption resonance band in the visible range and represent close-packed monolayers of nanoparticles, the average sizes of which increase from ~10 nm in the original samples to ~35–40 nm and ~45–60 nm in the annealed ones, depending on the annealing temperature. The influence of various factors on the spectral characteristics of samples, including the size of nanoparticles and electrodynamic interactions between nanoparticles, is discussed. It has been shown that all granular nanostructures studied, both initial and annealed, are highly resistive. It has been established that for the initial and annealed at 145 °C samples, near low values of the applied voltage, a dependence of the current on the irradiation wavelength can be traced, with its value changing up to two orders of magnitude for certain wavelengths.

Performance and failure modes of thermal barrier coatings deposited by EB-PVD on blades under real service conditions in gas turbine

Thermal barrier coatings (TBCs) with a double columnar crystal structure of CoCrAlY/YSZ, prepared using electron beam physical vapor deposition (EB-PVD), were applied to turbine blades and tested in real gas turbine conditions. This study investigates their failure mechanisms under both actual operating conditions and simulated external loads, using three-point bending tests. The performance of full-sized, TBC-coated blades was analyzed through finite element modeling, while the thermomechanical and mechanical properties of the coatings after service were measured to support the simulation and provide insights into the failure processes. A new degradation mode, characterized by penetration cracking, was observed in the EB-PVD coatings. This behavior is linked to the columnar grain structure of YSZ and CoCrAlY, lower operational temperatures, and the reduced thickness of the YSZ layer. Surface cracks in the YSZ coating primarily occurred in regions with large curvature, where stress concentrations are higher. This study offers new insights into the failure modes of TBCs under real gas turbine operating conditions.

THz-TDS characterization of stress evolution of EB-PVD TBCs under thermal cycling

The failure of thermal barrier coatings (TBCs) during service is a critical issue affecting aeroengine efficiency. In this study, electron beam physical vapor deposition (EB-PVD) TBCs were subjected to thermal cycling at 1100 °C. Terahertz time-domain spectroscopy (THz-TDS) was employed to characterize the relationship between the evolution of characteristic frequency and the number of thermal cycles, along with the development of stress in the ceramic layer. In situ tensile test revealed a linear correlation between the characteristic frequency and micro strain derived from THz-TDS data, with a proportional coefficient of −9.94 between the characteristic frequency and the slope of the refractive index curve. The results show that the stress evolution can be effectively monitored by recording the trend of characteristic frequency. During the non-failure stage, the characteristic frequency followed a parabolic trend as thermal cycles increased, influenced by the growth of thermally grown oxide (TGO), ceramic layer sintering, and thermal mismatch. Approaching the failure stage, stress evolution was dominated by the expansion of vertical cracks in the ceramic layer and the widening of transverse cracks at the interface, which corresponded to a sudden change in the characteristic frequency.

Design and fabrication of micro carbon dioxide sensor based on TiO2 thin film

Abstract A micro-electro-mechanical systems (MEMS)-based micro carbon dioxide sensor is fabricated using conventional photolithography, electron beam evaporation, and radio frequency sputtering techniques. The sensor consists of a titanium dioxide sensing layer, interdigital electrodes (IDEs), a platinum resistance temperature detector (RTD), and an aluminium oxide substrate. Given a working temperature greater than 300°C, the resistance of the titanium dioxide sensing layer increases linearly with an increasing carbon dioxide concentration. Fluctuations in the working temperature are detected by the RTD and compensated using a proportional-integral-derivative (PID) feedback control system implemented in LabVIEW. The temperature detection results reveal that the RTD has a sensitivity of 1.3 mV/°C. The sensor is calibrated using a standard carbon dioxide detector and is used to perform carbon dioxide sensing at working temperatures of 300°C, 350°C, and 400°C, respectively. It is shown that the highest sensitivity of (0.179 MΩ/ppm) and fastest response time (15 seconds) are attained at a working temperature of 350°C.

Bipolar resistive switching behavior of bilayer β-Ga2O3/WO3 thin film memristor device

This article investigates the bipolar resistive switching behavior of bilayer Au/β-Ga2O3/WO3 thin film (TF)/Ag heterostructure memristor device deposited using an electron beam evaporation technique. The purity of the deposited sample was confirmed by the XRD and FESEM with EDS characterizations. The root mean square roughness(RRMS) of single layer WO3 TF and heterolayer of Ga2O3/WO3 TF were obtained from the AFM analysis as 4.56nm and 2.20nm, respectively. The presence of more oxygen vacancies in WO3 sample was also confirmed by the XPS analysis. The optical measurement of the sample also revealed a bandgap of ~ 4.35eV for β-Ga2O3 TF and ~ 3.66eV for WO3 TF. Moreover, the bilayer Au/β-Ga2O3/WO3 TF/Ag heterostructure memristor device demonstrated bipolar resistive switching behavior with a good resistance ratio of ~ 182, an endurance of 300 cycles, and a data retention of 103s at room temperature. The device also yielded a low SET power of 1.17mW (at 1.74mA, +0.67V) and a low RESET power of 2.50mW (at 7.16mA, – 0.35V). The logarithmic current-voltage (I-V) relationship revealed that the switching behavior of the memristor device is mainly dominated by Ohmic conduction in LRS as well as Child’s square law, TCLC and Ohmic conductions in HRS. With the above parameters, the Au/β-Ga2O3/WO3 TF/Ag memristor device has the potential for future RRAM applications.

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.