Ceramic Target Materials Research Articles

Fabrication and characterization of ZnO/Zn2TiO4/ZnAl2O4 composite films by using magnetron sputtering with ceramic targets

Transparent conducting oxides (TCO), including ZnO/Zn2TiO4/ZnAl2O4 composite films, are of considerable importance in optoelectronic applications. We fabricated composite film assisted with DC magnetron sputtering using ceramic target material (ZnO, TiO2, and Al2O3 powders mixture). The influence of processing gases composition (0–50% O2–Ar) on film characteristics, including structural, optical, and electronic properties, is assessed. All films contain hexagonal wurtzite ZnO structure and ZnAl2O4, Zn2TiO4 spinel phases, with (002), (100), and (101) as dominant orientation by increasing oxygen contents. The transmittance of deposited films is above 81% (except for 50% oxygen), and the bandgap lies between 3.73 and 3.28 eV (reduced by oxygen addition). The carrier concentration and mobility increase with oxygen addition up to 25%, and resistivity decreases by increasing oxygen contents. This study shows that using ceramic targets, the compound film with variable composition, structural and optoelectronic properties can be obtained by altering the gases admixture.

Preparation of superior IGZO ceramics by two-step sintering for application in IGZO thin film fabrication

The preparation method of advanced ceramics that serve as target materials, has been the key challenge to produce high quality thin film transistors (TFTs) with the desired properties. In this study, a novel two-step sintering (TSS) process was successfully applied to fabricate indium gallium zinc oxide (IGZO) ceramics. The sintering behaviour of the IGZO compacts was investigated in detail and it was established that the first step optimum temperature should be in the range of 1400–1500 ℃, while for the second step should be 1350℃ with a dwell time of 12 h. Using this method, the relative density, average grain size and resistivity of the IGZO ceramics could reach 99.5%, 4–5 μm and 2.31 mΩ⋅cm, respectively. The corresponding IGZO thin films produced from the ceramic through sputter deposition had an average transmittance of over 88% and a low resistivity of 3.56 mΩ⋅cm. These excellent properties suggest that TSS has considerable potential as a viable approach for the preparation of ceramic target materials, which find application in the fabrication of TFTs.

A model incorporating damage evolution to predict the penetration behavior of a ceramic target subjected to the long projectile impact

Predicting the ballistic performance of a ceramic armor composite system requires the accurate constitutive formulation of the ceramic target material. In this study, the analytical spherical cavity expansion model was modified to simulate the penetration process of a ceramic target impacted by a long projectile, and then validated by the data in the literature. Specifically a damage evolution parameter that characterizes the modulus degradation in the ceramic was proposed and incorporated into the model. It was found that the prediction is more accurate when the model includes damage evolution. Parametric modeling further reveals that the properties of the projectile and target materials have a significant effect on the penetration response. The target resistance is sensitive to the damage evolution, especially in the ceramic of higher dynamic compressive strength and lower tensile strength. The modified model enables the selection of target materials for penetration resistance in terms of not just strength but also toughness.

Implementation of a rate dependent tensile failure model for brittle materials in ABAQUS

Plate impact tests present the dynamic response of materials under impact loading conditions. Commercial finite element software can be used to simulate plate impact test and implement the desired constitutive or damage model of materials. Implementation of plate impact tests also allows researchers to study the dynamic response of heterogeneous materials in micro-scale. A plate impact test for brittle materials has been simulated in this study using ABAQUS software. Micro-cracking in the brittle ceramic materials causes the samples to behave inelastically under compressive shock loading. The release waves from the free surface of the flyer and rear surface of the target release the compressed materials. Consequently, micro-cracks rapidly open and extend, causing the damage to grow. Thus, the Taylor–Chen–Kuszmaul (TCK) model was implemented using a VUMAT FORTRAN ABAQUS/Explicit subroutine with respect to tension with damage growth and to compression plasticity for ceramic plates (target). The objective of the study is to describe the implementation of a state- and pressure-dependent constitutive model that describes tensile damage in brittle materials using a finite element method. An iteration second-order Runge–Kutta method has been developed for further implementation. Some parameters, such as damage nucleation and strain rate sensitivity, are calibrated based on the ability of the model to reproduce the experimental results. The damage model introduced in this study has been employed successfully to match the experimental results for an AD-85 ceramic target material.

Synthesis of Zn2SnO4 powders via hydrothermal method for ceramic targets

The preparation of (SnO2)x(ZnO)1−x powder as a ceramic target material via hydrothermal synthesis within a broad range of x values (x=0–1) was investigated. The phase development and particle characteristics of the Zn2SnO4 powders were evaluated. The phase formations of the (SnO2)x(ZnO)1−x system in the range from x=0.0 to 1.00 were mapped, and the ZnO, SnO2 and Zn2SnO4 phases were found to depend on the changing x value. The effects of the processing parameters, including the treatment temperature (180–220°C), time (0–24h) and initial concentrations of precursors (Sn:Zn=0.125:0.3, 0.2:0.48, 0.25:0.6, 0.35:0.84, 0.5:1.20), on the formation mechanism of Zn2SnO4 were discussed in detail. Almost single phase Zn2SnO4 occurs only when x=0.29 (Zn/Sn=2.4:1) for the (SnO2)x(ZnO)1−x composite system at 220°C for 24h. The results reveal that the target prepared from synthesized Zn2SnO4 powder can be successfully used to develop thin film transistor channels.

Bias voltage dependence properties of Nb-doped indium tin oxide thin films by RF magnetron sputtering at room temperature

Niobium doped indium tin oxide (ITO:Nb) thin films were fabricated on glass substrates by RF magnetron sputtering from one piece of ceramic target material at room temperature. The bias voltage dependence of properties of the ITO:Nb films were investigated by adjusting the bias voltage. Structural, electrical and optical properties of the films were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), UV–visible spectroscopy, and electrical measurements. XRD patterns showed a change in the preferential orientations of polycrystalline crystalline structure from (222) to (400) crystal plane with the increase of negative bias voltage. AFM analysis revealed that the smooth film was obtained at a negative bias voltage of -120V. The root mean square (RMS) roughness and the average roughness are 1.37nm and 1.77nm, respectively. The films with the lowest resistivity as low as 1.45×10−4Ωcm and transmittance over 88% have been obtained at a negative bias voltage of −120V. Band gap energy of the films, depends on substrate temperature, varied from 3.56eV to 3.62eV.

Effect of thickness on optoelectrical properties of Nb-doped indium tin oxide thin films deposited by RF magnetron sputtering

Niobium-doped indium tin oxide (ITO:Nb) thin films are prepared on glass substrates with various film thicknesses by radio frequency (RF) magnetron sputtering from one piece of ceramic target material. The effects of thickness (60–360 nm) on the structural, electrical and optical properties of ITO: Nb films are investigated by means of X-ray diffraction (XRD), ultraviolet (UV)-visible spectroscopy, and electrical measurements. XRD patterns show the highly oriented (400) direction. The lowest resistivity of the films without any heat treatment is 3.1×10−4Ω·cm−1, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 17.6 N·S and 1.36×1021 cm−3, respectively. Band gap energy of the films depends on substrate temperature, which varies from 3.48 eV to 3.62 eV.

Ceramic Target Materials for Sputtering Applications

The lecture will give an overview of the manufacturing technique of ceramic target materials based on ZnO and TiO2. Sintering and plasma spraying techniques are typically used. Also special bonding procedures have to be established in order to join ceramic target materials to metallic carriers. Metallic and ceramic target materials will be compared with respect to target materials processing and sputtering experiences as well. In addition planar and cylindrical targets will be briefly discussed as sputtering of large substrates is strongly moving towards cylindrical cathode applications.

Removal and transfer of material in laser-assisted physical vapour deposition of ceramics

The removal and transfer of ceramic target materials in laser-assited physical vapour deposition are investigated as a function of laser parameters and processing variables. Removal was measured by a microbalance and characteristics of angular distribution, transfer by emission spectroscopy and high-speed photography. The composition, the ionization state of the particles and the electron temperature of the vapour/plasma govern the structures of the thin films deposited, which are discussed in view of applications.

Impact damage model for ceramic materials

The fracture process in ceramic materials upon impact loading is complex in nature. Most often, the brittle ceramic deforms inelastically due to microcracking under shock (compression) loading. At high-velocity impact, the shock generated microcracks rapidly open and extend under subsequent tension (due to the release waves from the stress-free boundaries) leading to complete pulverization of the ceramic materials. The main objective of this paper is to model the damage process in ceramics due to impact loading. A computationally oriented continuum damage-based constitutive model is considered. Several modifications incorporating strain rate and damage effects on the compressive strength have been introduced into the model. Results are presented in terms of numerical simulations of a plate-impact test configuration. Effects of the model parameters on the compressive strength and spall strength are described. The proposed damage model has been used successfully to match the measured stress history from a plate-impact experiment on AD-85 (85% aluminum oxide) ceramic target material.