Structural,optical, and electrical properties of conducting p-type transparent Cu–Cr–O thin films

Cu–Cr–O films were prepared by DC magnetron co-sputtering using Cu and Cr targets on quartz substrates. The films were then annealed at temperatures ranging from 400 °C to 900 °C for 2 h under a controlled Ar atmosphere. The as-deposited and 400 °C-annealed films were amorphous, semi-transparent, and insulated. After annealing at 500 °C, the Cu–Cr–O films contained a mixture of monoclinic CuO and spinel CuCr₂O₄ phases. Annealing at 600 °C led to the formation of delafossite CuCrO₂ phases. When the annealing was further increased to temperatures above 700 °C, the films exhibited a pure delafossite CuCrO₂ phase. The crystallinity and grain size also increased with the annealing temperature. The formation of the delafossite CuCrO₂ phase during post-annealing processing was in good agreement with thermodynamics. The optimum conductivity and transparency were achieved for the film annealed at approximately 700 °C with a figure of merit of 1.51×10⁻⁸ Ω⁻¹ (i.e., electrical resistivity of up to 5.13 Ω-cm and visible light transmittance of up to 58.3%). The lower formation temperature and superior properties of CuCrO₂ found in this study indicated the higher potential of this material for practical applications compared to CuAlO₂.     

Optical and Microwave Dielectric Properties of Phase Pure (K0.5Na0.5)NbO3 Thin Films Deposited by RF Magnetron Sputtering

(K_0.5Na_0.5)NbO₃ (KNN) thin films have been deposited onto Pt/Ti/SiO₂/Si and quartz substrates by RF magnetron sputtering. The films were deposited at 400°C with the variation in oxygen mixing percentage (OMP) ratio from 0% to 100% and annealed at 700°C in oxygen atmosphere. The crystallinity of the films is found to be increased with increased OMP. Dielectric properties of the films were examined over the frequency range from 1 kHz to 1 MHz and the temperature range of 30°C to 400°C. The Curie temperature of the films was found to be in the range 369°C–373°C. For the first time, the split postdielectric resonator (SPDR) method was used to measure the microwave (10–20 GHz) dielectric properties of KNN thin films. The optical properties of as‐deposited and annealed KNN thin films were investigated by means of transmittance spectra. The optical bandgap is calculated by using the Tauc relation, and found to be in the range 4.34–4.40 eV and 4.29–4.37 eV for the as‐deposited and annealed films, respectively. The refractive index (n_700nm) of the films found to be in the range 1.98–2.01 and 1.99–2.07 for as‐deposited and annealed films, respectively. The refractive index dispersion is analyzed by using Wemple–DiDomenico (W–D) single‐oscillator model. The effect of annealing and OMP on the refractive index, packing density and W–D parameters has been investigated. The average single oscillator energy (E_o) and dispersion energies (E_d) of the annealed KNN thin films are in the range of 6.17–7.16 eV and 18.77–22.19 eV, respectively. AC‐conductivity of the annealed films was analyzed by using double power law. Ag/KNN/Pt thin films followed the ohmic conduction (J ∝ E^α, where α ~1) and the low leakage current density obtained for the deposited at 100% O₂ is 3.14 × 10^?5 A/cm² at 50 kV/cm.     

Solvent-deficient method lowers grain-boundary resistivity of doped ceria

Nanoparticles of gadolinium-doped cerium oxide (GDC) were synthesized using solvent-deficient method and their sinterability and electrical properties were investigated using the powder and cold sintering process. The GDC powder was uniaxially pressed into cylindrically-shaped pellets with a mixture of nitric acid and hydrogen peroxide at 200°C to encourage particle arrangement during forming process. These bulk samples were annealed using two different temperature profiles: at 800°C for 5 hours and at 1300°C for 1 minute—800°C for 5 hours. The samples produced using HNO₃/H₂O₂ mixture showed higher relative density than ones without it. Ionic conductivity of the sample sintered through the two-step profile was obtained from electrochemical impedance spectroscopy. Although the grain conductivity for the samples (8.0 × 10⁻³ S cm⁻¹ at 500°C, and 3.3 × 10⁻² S cm⁻¹ at 700°C) is on par with a conventionally sintered sample, the measured total conductivity (3.9 × 10⁻³ S cm⁻¹ at 500°C, and 2.5 × 10⁻² S cm⁻¹ at 700°C) is about 10 times higher than the conventionally sintered one and is comparable to the values seen in the previous studies for GDC which employed higher sintering temperature, pointing to the effectively lower grain-boundary impedance. This result could be attributed to no significant phase segregation along grain boundaries due to the low-temperature processing.     

Annealing temperature-dependent structural and electrical properties of (Ta2O5)1-x - (TiO2)x thin films,x ≤ 0.11

(Ta₂O₅)_1-x- (TiO₂)_x (TTO_x) thin films, with x = 0, 0.03, 0.06, 0.08, and 0.11, were deposited using magnetron direct current (DC) sputtering method onto the P/boron-silicon (1 0 0) substrates by varying areas of Tantalum and Titanium metallic targets, in oxygen environment at ambient temperature. The as-deposited thin films were annealed at temperatures ranging from 500 to 800 °C. Generally, the formation of the Ta₂O₅ structure was observed from the X-ray diffraction measurements of the annealed films. The capacitance of prepared metal– oxide– semiconductor (MOS) structures of Ag/TTO_x/p-Si was measured at 1 MHz. The dielectric constant of the deposited films was observed altering with varying composition and annealing temperature, showing the highest value 71, at 1 MHz, for the TTO_x films, x = 0.06, annealed at 700 °C. With increasing annealing temperature, from 700 to 800 °C, the leakage current density was observed, generally decreasing, from 10^?5 to 10^?8 A cm^?2, for the prepared compositions. Among the prepared compositions, films with x = 0.06, annealed at 800 °C, having the observed value of dielectric constant 48, at 1 MHz; and the leakage current density 2.7 × 10^?8 A cm^?2, at the electric field of 3.5 × 10⁵ V cm^?1, show preferred potential as a dielectric for high-density silicon memory devices.     

Electro-optical performances of nanostructured SrTiOx films: The effect of plasma power,Ar/O2 ratio and annealing

The present work evaluates the effects of plasma power and oxygen mixing ratios (OMRs) on structural, morphological, optical, and electrical properties of strontium titanate SrTiO_x (STO) thin films. STO thin films were grown by magnetron sputtering, and later thermal annealing at 700°C for 1 h was applied to improve film properties. X-ray diffraction analysis indicated that as-deposited films have amorphous microstructure independent of deposition conditions. The films deposited at higher OMR values and later annealed also showed amorphous structure while the films deposited at lower OMR value and annealed have nanocrystallinity. In addition, all as-deposited films were highly transparent (~80%–85%) in the visible spectrum and exhibited well-defined main absorption edge, while the annealing improved transparency (90%) within the same spectrum. The calculated direct and indirect optical band gaps for films were in the range of 3.60-4.30 eV as a function of deposition conditions. The refractive index of the films increased with OMRs and the postdeposition annealing. The frequency dependent capacitance measurements at 100 kHz were performed to obtain film dielectric constant values. High dielectric constant values reaching up to 100 were obtained. All STO samples exhibited more than 2.5 μC/cm² charge storage capacity and low dielectric loss (less than 0.07 at 100 kHz). The leakage current density was relatively low (3 × 10⁻⁸Acm⁻² at +0.8 V) indicating that STO films are promising for future dynamic random access memory applications.     

Enhancement of thermoelectric performance of N-type Bi2Te3 based thin films via in situ annealing during magnetron sputtering

In this work, n-type Bi₂Te₃ based thin films were prepared in 300 °C via DC magnetron sputtering, and influences of sputtering power and annealing time on thermoelectric properties of films were investigated. The raise of sputtering power brings about the improvement of deposited rate and enhancement of grain size. Taking the consideration that the large-sized grains are to phonon scattering, we determine the medial power of 30 W as the basic technical parameters for the purpose of further optimizing performance through an in situ annealing process. Subsequently, thin-film treated by in situ annealing process acts out an obvious reduction in electrical conductivity attributed to the decrease in carrier concentration. Especially, the film annealed for 40 min shows an enhancement in the Seebeck coefficient and leads to a maximum power factor 0.82 m W m⁻¹ K⁻² at 543 K.     

Enhancement of the electrochemical performance of LiCoPO4 by Fe doping

LiCoPO₄ is an attractive cathode material, but it undergoes poor electronic conductivity and electrochemical performance. This performance is enhanced by substituting iron antisite Cobalt to reduce the direct interaction between the cathode and the electrolyte. Thus, LiCoPO₄ doped with Fe was synthesized by the microwave-assisted solvothermal route at 220 °C. According to X-ray diffraction analysis, a single orthorhombic Pn21a phase (a = 10.02 Å, b = 6.71 Å and c = 4.96 Å) was obtained, which transited to Pnma phase (a = 10.21 Å b = 5.92 Å and c = 4.76 Å) after annealing at 700 °C in air. The morphology and particle size of the sample changed after annealing, as shown by TEM. The electrochemical cycling of an annealed sample showed the initial discharge capacity of 125mAh g⁻¹ compared to 12 mAh g⁻¹ for the non-annealed sample, which can be regarded as a partial coating by FePO₄ as obtained from X-ray absorption spectroscopy analysis.     

Construction of multiple heterogeneous interface and its effect on microwave absorption of SiBCN ceramics

Iron-containing siliconboron carbonitride (SiBCN) ceramics with multiple heterogeneous interfaces were fabricated using the microstructural design and polymer-derived ceramics (PDC) approach. The characterization results revealed the in-situ generation of nanocrystals, including graphite, belt-like silicon nitride (Si₃N₄), and silicon carbide (SiC) whiskers, in amorphous SiBCN matrix after annealing. At the same time, these dielectric lossy phases successfully constructed multiple heterogeneous interfaces and three-dimensional network structures. Consequently, the conductivity of the ceramics increased from 4.49 × 10⁻⁹ (annealed at 800 °C) to 0.67 × 10⁻⁴ S cm⁻¹ (annealed at 1600 °C). The real part of permittivity improved from 4.57–3.36 (annealed at 800 °C) to 10.90–8.38 (annealed at 1600 °C) in the frequency range of 2–18 GHz. The formation of multiple heterogeneous interfaces caused interfacial polarization and increased the multiple relaxations, which ultimately led to a superior microwave absorption property with a minimum reflection loss (RL_min) of −34.28 dB and an effective absorption bandwidth (EAB) of 3.76 GHz (8.64–12.4 GHz).     

Influence of post-deposition annealing on electrical and optical properties of (Ta2O5)1-x - (TiO2)x thin films,x ≤ 0.08

Tantalum (Ta) and titanium (Ti) metal targets were direct current (DC) magnetron sputtered in the oxygen environment by varying its relative areas to deposit (Ta₂O₅)_1-x- (TiO₂)_x (TTO_x) thin films, with x = 0, 0.03, 0.06, and 0.08, onto the boron-doped p-silicon (1 0 0) and optically polished quartz substrates, at room temperature; and were annealed at 500, 600, 700, and 800 °C, for 1.5 h. The thin films annealed at and above 600 °C show the Ta₂O₅ structure. The leakage current density and capacitance-voltage (C–V) characteristics were measured for TTO_x, x ≤ 0.08, assisted Ag/TTO_x/p-Si metal– oxide– semiconductor (MOS) structures. The leakage current density was found minimum, for the films annealed at 800 °C, for all the prepared TTO_x films, x ≤ 0.08. The minimum leakage current density 1.6 × 10^?8 A/cm², at 3.5 × 10⁵ V/cm electric field, was observed for x = 0.03, annealed at 800 °C, among the prepared compositions. The prepared TTO_0.03 films, annealed at 700 °C show maximum dielectric constant 39, at 1 MHz. The optical parameters, viz., refractive index (n), extinction coefficient (k), and optical band gap (E_g) of the films, with x = 0.03, prepared on quartz substrates, were determined from their optical transmittance plots. The values of n and k of the crystalline films were observed increasing from 2.123 to 2.143, and 0.099 to 0.130, respectively, at 550 nm wavelength; and E_g decreasing from 3.95 to 3.89 eV with the increasing annealing temperature, from 600 to 800 °C. Ohmic emission, in the lower electric field; Schottky and space-charge- limited current conduction mechanisms, in the intermediate to higher electric fields, were generally envisaged from the current-voltage characteristics in the prepared Ag/TTO_0.03/p-Si structures.     

Enhanced electrical properties of In-Ga-Sn-O thin films at low-temperature annealing

Electrical and optical properties of In-Ga-Sn-O (IGTO) thin films deposited by radio-frequency magnetron sputtering were investigated according to annealing temperatures. While IGTO films remained an amorphous phase even after a heat treatment at temperature up to 500 °C, Hall measurements showed that annealing temperature had a significant impact on electrical properties of IGTO thin films. After investigating a wide range of annealing temperatures for samples from as-deposited state to 500 °C, IGTO film annealed at 200 °C exhibited the best electrical performance with a conductivity of 229.31 Ω^?1cm^?1, a Hall mobility of 36.89 cm²V^?1s^?1, and a carrier concentration of 3.85 × 10¹⁹ cm^?3. Changes in proportions of oxygen-related defects and percentages of Sn²⁺ and Sn⁴⁺ ions within IGTO films according to annealing temperatures were analyzed with X-ray photoelectron spectroscopy to determine the cause of the superb performance of IGTO at a low temperature. In IGTO films annealed at 200 °C, Sn⁴⁺ ions acting as donor defects accounted for a high percentage, whereas hydroxyl groups working as electron traps showed a significantly reduced percentage compared to the as-deposited film. Optical band gaps of IGTO films obtained from UV–visible spectrum were 3.38–3.47 eV. The largest band gap value of 3.47 eV for the IGTO film annealed at 200 °C could be attributed to an increase in Fermi-level due to an increase of carrier concentration in the conduction band. These spectroscopic results well matched with electrical properties of IGTO films according to annealing temperatures. Excellent electrical properties of IGTO thin films annealed at 200 °C could be largely due to Sn donors besides oxygen vacancies, resulting in a significant increase in free carriers despite a low annealing. temperature.     

Sol–gel synthesis of Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte

The effect of calcination on Li ion conductivity of Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) solid electrolyte prepared by a sol–gel method is examined. The Li ion conductivity of LAGP increases with calcination temperature. After reaching maximum conductivity at 850 °C, the conductivity decreases with increase of the calcination temperature. The calcination holding time also strongly affects Li ion conductivity of LAGP. The conductivity increases with holding time until 12 h and then decreases. It is found that the control of crystallization rate is critical to obtain bulk LAGP with high Li ion conductivity. The highest bulk and total conductivities at 30 °C are 9.5×10⁻⁴ and 1.8×10⁻⁴ S cm⁻¹, respectively, obtained for the bulk LAGP calcined at 850 °C for 12 h.     

Effects of annealing temperature on the phase formation,optical, photoluminescence and magnetic properties of sol-gel YFeO3 films

YFeO₃ (YFO) thin films were deposited onto quartz substrates via sol-gel spin-coating technique and annealed at different temperature ranged between 650 and 900 °C. The impact of annealing temperature on the phase formation, microstructural, optical, photoluminescence (PL) and magnetic properties of the films were systematically investigated. X-ray diffraction analysis revealed an amorphous structure in film annealed at 650 °C and formation of hexagonal-YFO (h-YFO) phase in films annealed at 750–800 °C. The films annealed at 850–900 °C exhibited an orthorhombic-YFO (o-YFO) structure. Atomic force microscopy images of h-YFO films showed homogeneous surface with uniform particles size and shape. The particle size increased and had irregular shape in o-YFO films. The average particle size was 44 and 117 nm, while the root square roughness was 1.38 and 2.55 nm for h- and o-YFO films annealed at 750 and 850 °C, respectively. The optical band gap (E_g) was 2.53 and 2.86 eV for h- and o-YFO films annealed at 750 and 850 °C, respectively. The PL spectra of h-YFO films were red-shifted compared with that of o-YFO films. The PL emission related to near band edge was observed at 459.0 and 441.9 nm for h- and o-YFO films annealed at 750 and 850 °C, respectively. The magnetization was enhanced with the increasing of annealing temperature and has the value of 4.8 and 12.5 emu/cm³ at 5000 Oe for h- and o-YFO films annealed at 750 and 850 °C, respectively.     

Sol-gel route to nanocrystalline Eu2Ti2O7 films with tailored structural and optical properties

We present a generic sol-gel approach for the preparation of highly transparent europium titanate Eu₂Ti₂O₇ films with tailored structural and optical properties. The films were prepared by a sol-gel process and thermally treated in a rapid thermal annealing furnace. We determined the effects of the annealing temperature on structural, morphological, and optical properties of the films. We evaluated film's optical constants. The size of the primary nanocrystals and the film's refractive index were tailored by the annealing temperature. The crystallization of Eu₂Ti₂O₇ started at 800°C and the nanocrystals grew with increasing annealing temperature reaching the size from 20 nm to 100 nm. The energy of nanocrystal growth was 21 ± 3 kJ·mol⁻¹. Increasing nanocrystal size caused the regular growth of the refractive index recorded at 632 nm from 2.07 to 2.17 for the films annealed at 800°C and 1200°C, respectively. These results provide fundamental information about the effects of the structure and the morphology of the films on their optical properties. The presented approach can be extended to other rare earth-doped titanates and these films can be used as passive protective coatings as well as active materials suitable for photonic and spintronic applications.     

Mechanical properties and thermal stability of SiBCN films prepared by ion beam assisted sputter deposition

The high hardness, exceptional high temperature stability, and oxidation resistance of bulk Si–B–C–N ceramics have led to the expectation that these materials will be good candidates for superior coating materials in high-temperature applications. In this study, SiBCN films were prepared using ion beam assisted sputter (IBAS) deposition, and the mechanical properties and thermal stabilities of the films at 600, 700, and 800 °C in air were investigated. In particular, the effects of the ion beam assist on the properties of the SiBCN films were examined. The SiBCN films were deposited on Si plates by sputtering a target composed of Si + BN + C using a 2-keV Ar⁺ ion beam. A low-energy N₂⁺ and Ar⁺ mixed ion beam irradiated the samples during the sputter deposition. The Si content in the SiBCN films was controlled by changing the Si/(BN + C) ratio of the target. BCN films were also deposited for comparison. The composition and chemical bonding structure of the prepared films were investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. We found that c-BN bonds were formed in the ion-assisted BCN film. The oxide layer thickness on the SiBCN films after thermal annealing decreased due to the IBAS deposition and an increase in the Si content. Ion-assisted SiBCN films annealed at 800 °C showed the highest hardness of 20 GPa.     

Mechanical Characterization of Annealed ZrB2–SiC Composites

Composites consisting of 70 vol% ZrB₂ and 30 vol% α‐SiC particles were hot pressed to near full density and subsequently annealed at temperatures ranging from 1000°C to 2000°C. Strength, elastic modulus, and hardness were measured for as‐processed and annealed composites. Raman spectroscopy was employed to measure the thermal residual stresses within the silicon carbide (SiC) phase of the composites. Elastic modulus and hardness were unaffected by annealing conditions. Strength was not affected by annealing at 1400°C or above; however, strength increased for samples annealed below 1400°C. Annealing under uniaxial pressure was found to be more effective than annealing without applied pressure. The average strength of materials annealed at 1400°C or above was ~700 MPa, whereas that of materials annealed at 1000°C, under a 100 MPa applied pressure, averaged ~910 MPa. Raman stress measurements revealed that the distribution of stresses in the composites was altered for samples annealed below 1400°C resulting in increased strength.     

The effect of annealing on electrical properties of fluorinated amorphous carbon films

Fluorinated amorphous carbon (a–C:F) films have been deposited by electron cyclotron resonance chemical vapor deposition (ECR–CVD) at room temperature using C₄F₈ and CH₄ as precursor gases. The chemical compositions and electrical properties of a–C:F films have been studied by X-ray photoelectron spectroscopy (XPS), capacitance–voltage (C–V) and current-voltage (I–V) measurements. The results show that C–CF_x and C–C species of a–C:F films increase and fluorine content decreases after annealing. The dielectric constant of the annealed a–C:F films increases as a result of enhancement of film density and reduction of electronic polarization. The densities of fixed charges and interface states decrease from 1.6 × 10¹⁰ cm^− 2 and (5–9) × 10¹¹ eV^− 1 cm^− 2 to 3.2 × 10⁹ cm^− 2 and (4–6) × 10¹¹ eV^− 1 cm^− 2 respectively when a–C:F films are annealed at 300 °C. The magnitude of C–V hysteresis decreases due to reduced dangling bonds at the a–C:F/Si interfaces after heat treatment. The conduction of a–C:F films shows ohmic behavior at lower electric fields and is explained by Poole–Frankel (PF) mechanism at higher electric fields. The PF current increases indicative of reduced trap energy when a–C:F films are subjected to higher annealing temperatures.     

Dielectric and thermal properties of AlN ceramics

The effects of slow-cooling and annealing conditions on dielectric loss, thermal conductivity and microstructure of AlN ceramics were investigated. Y₂O₃ from 0.5 to 1.25 mol% at 0.25% increments was added as a sintering additive to AlN powder and pressureless sintering was carried out at 1900 °C for 2 h in a nitrogen flowing atmosphere. To improve the properties, AlN samples were slow-cooled at a rate of 1 °C min⁻¹ from 1900 to 1750 °C, subsequently cooled to 970 °C at a rate of 10 °C min⁻¹ and then annealed at the same temperature for 4 h. AlN and YAG (5Al₂O₃/3Y₂O₃) were the only identified phases from XRD. AlN doped with 0.5 and 0.75 mol% Y₂O₃ had a low loss of <2.0 × 10⁻³ and a high thermal conductivity of >160 W m⁻¹ °C⁻¹.     

Deposition of highly oriented lanthanum nickel oxide thin film on silicon wafer by CSD

This paper describes the orientation control and the electrical properties of the chemical solution deposition (CSD) derived LaNiO₃ (LNO) thin film. The LNO precursor solutions were prepared using lanthanum nitrate and nickel acetate as La and Ni source, and ethanol or 2-methoxyethanol and 2-aminoethanol mixed solution as solvents. The LNO films were spin-coated using these precursor solutions and annealed at the temperature from 500 to 700 °C. The resulting LNO film annealed at 700 °C derived from 2-methoxyethanol and 2-aminoethanol mixed solvent exhibited (1 0 0)-orientation, with some surface cracks and pores, and relatively higher resistivity of 2.49 × 10⁻³ Ω cm. The LNO film derived from 2-methoxyethanol and 2-aminoethanol mixed solvent annealed at 700 °C in an oxygen atmosphere showed highly (1 0 0)-orientation, with higher density, a few cracks and pores, and exhibited a good electrical resistivity of 7.27 × 10⁻⁴ Ω cm.     

Synergistic modification of properties in Ba[(Zn0.8Mg0.2)1/3Nb2/3]O3 ceramics through ordered domain engineering

The ordered domain engineering was investigated for Ba[(Zn_0.8Mg_0.2)_1/3Nb_2/3]O₃ microwave dielectric ceramics to synergistically modify the physical properties especially the temperature coefficient of resonant frequency τ_f and quality factor Q value together with the thermal conductivity. The ordered domain structure could be tailored and controlled by the post-densification annealing, and the fine ordered domain structures with high ordering degree and low-energy domain boundary were obtained in the present ceramics annealed around 1400°C for 24 h, where the Qf value was improved from 51 000 to 118 000 GHz, τ_f was suppressed from 30 to 25.5 ppm/°C. Moreover, the thermal conductivity at room temperature was increased from 3.79 to 4.30 W m⁻¹ K⁻¹, and the Young's modulus was improved from 98 to 214 GPa. The present work provided a promising approach for synergistic modification of physical properties in Ba-based complex perovskite microwave dielectric ceramics.     

Effect of annealing temperature on ferroelectric electron emission of sol–gel PZT films

In this work, the influence of annealing temperature on the ferroelectric electron emission behaviors of 1.3-μm-thick sol–gel PbZr_0.52Ti_0.48O₃ (PZT) thin film emitters was investigated. The results revealed that the PZT films were crack-free in perovskite structure with columnar-like grains. Increasing annealing temperature led to the growth of the grains with improved ferroelectric and dielectric properties. The remnant polarization increased slightly from 35.3 to 39.6 μC/cm² and the coercive field decreased from the 56.4 to 54.6 kV/cm with increasing annealing temperature from 600 to 700 °C. The PZT film emitters exhibited remarkable ferroelectric electron emission behaviors at the threshold voltage above 95 V. The film annealed at 700 °C showed a relatively lower threshold voltage and higher emission current, which is related to the improved ferroelectric and dielectric properties at higher annealing temperature. The highest emission current achieved in this work was around 25 mA at the trigger voltage of 160 V.