Optimization Of Deposition Parameters Research Articles

Electrical and optical studies of Ga-doped ZnO thin films

Nanostructure Ga-doped zinc oxide (GZO) thin films with highly (0 0 2) preferred orientation were fabricated on glass substrates, using radio frequency magnetron sputtering with an GZO ceramic target (The Ga2O3 contents was about 3 wt%) and different deposition conditions. The structural features, surface morphology and electrical and optical properties of the GZO thin films were studied, in terms of the deposition parameters. A Grey-based Taguchi method was used to determine the optimal deposition parameters for GZO thin films by considering multiple performance characteristics. The response graph and table for each level of the deposition parameters forms the Grey relational grade and the optimal levels of the deposition parameters were chosen. The experimental results show that the process pressure and the thickness make the most significant contribution to the overall performance. In the confirmation runs, Grey relational analysis showed that the improvement in deposition rate is 14.2 %, the improvement in electrical resistivity 38.1 % and the improvement in optical transmittance is 1.2 %. Annealing in a vacuum further improved the crystalline quality and optoelectronic performances of the GZO thin films.

A study of the effect of waste from production of fluoropolymers on properties of zinc-fluoropolymer composite electrochemical coatings

Possibility of depositing zinc-fluoroplastic composite electrochemical coatings from ammonium chloride electrolytes, with the role of a dispersed phase played by liquid wastes from production of fluoropolymers and secondary suspensions of F-4D and F-4MD fluoroplastics, was studied. The optimal deposition parameters of composite coatings were determined. The effect of liquid wastes on the buildup of internal stresses in coatings and on the corrosion resistance of zinc-fluoroplastic composite electrochemical coatings was examined.

Thickness dependence of Cd0.825Pb0.175S thin film properties

State-of-the-art, novel and inexpensive chemical deposition route was selected for the preparation of Cd0.825Pb0.175S thin films. Optimized deposition parameters were: time=60min, temperature=80°C, speed of substrate rotation=65±2rpm and pH=10.5±0.1. XRD analysis of polycrystalline Cd0.825Pb0.175S thin films revealed mixture of hexagonal and cubic phases. Morphological features rigorously define nucleation and subsequent growth of thin film layers. Detailed investigations on power output curves underline the boost in conversion efficiency from 0.184% to 0.245% with increase in layer thickness. Low conversion efficiency in the present case is attributed to the higher photoelectrode resistance and significant light absorption by the electrolyte.

Deposition of c-axis orientation aluminum nitride films on flexible polymer substrates by reactive direct-current magnetron sputtering

Aluminum nitride (AlN) piezoelectric thin films with c-axis crystal orientation on polymer substrates can potentially be used for development of flexible electronics and lab-on-chip systems. In this study, we investigated the effects of deposition parameters on the crystal structure of AlN thin films on polymer substrates deposited by reactive direct-current magnetron sputtering. The results show that low sputtering pressure as well as optimized N2/Ar flow ratio and sputtering power is beneficial for AlN (002) orientation and can produce a highly (002) oriented columnar structure on polymer substrates. High sputtering power and low N2/Ar flow ratio increase the deposition rate. In addition, the thickness of Al underlayer also has a strong influence on the film crystallography. The optimal deposition parameters in our experiments are: deposition pressure 0.38Pa, N2/Ar flow ratio 2:3, sputtering power 414W, and thickness of Al underlayer less than 100nm.

Control of Heteroepitaxial Growth of CaCu3Ti4O12 Films on SrTiO3 Substrates by MOCVD

AbstractThin films of CaCu3Ti4O12 (CCTO) are successfully deposited by metal‐organic (MO)CVD on (001)SrTiO3 substrates. An interesting approach, based on a molten multi‐component precursor source, is applied. The molten mixture consists of the Ca(hfa)2•tetraglyme, Ti(tmhd)2(OiPr)2, and Cu(tmhd)2 [Hhfa = 1,1,1,5,5,5‐hexafluoro‐2,4‐pentanedione; tetraglyme = 2,5,8,11,14‐pentaoxapentadecane; Htmhd = 2,2,6,6‐tetramethyl‐3,5‐heptandione; OiPr = iso‐propoxide] precursors. It is also found that, in the present case of a relatively large lattice mismatch (∼5%), the epitaxial growth can be achieved by a careful optimization of deposition parameters. Film structural and morphological characterization is carried out using several techniques; X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A complete comparison between films deposited by two main processes is carried out in order to understand the kinetic and thermodynamic issues involved in the MOCVD epitaxial growth.

Effects of Deposition Parameters and Annealing Temperatures on the Characteristics of the Sr<sub>0.6</sub>Ba<sub>0.4</sub>Nb<sub>2</sub>O<sub>6</sub> Thin Films

Sr0.6Ba0.4Nb2O6 (SBN) thin films were prepared by radio frequency (RF) sputtering onto the SiO2/Si/Al and Pt/Ti/Si substrates to form the MFIS and MFM structures. Their deposition rates increased with decreasing oxygen concentration and with increasing RF power. Their optimal deposition parameters were the substrate temperature of 500°C, chamber pressure of 10 mTorr, oxygen concentration of 40%, and RF power of 120W, respectively. The rapid temperature annealing (RTA) process had large effects on the grain growth of the SBN thin films. The effects of different RTA temperatures on the leakage current density - electrical field curves and the capacitance - voltage curves of the SBN thin films were also investigated.

Sprayed lanthanum doped zinc oxide thin films

Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

Growth of high Ge content SiGe on (110) oriented Si wafers

Growth of high (above 40%) Ge content SiGe by applying silane and dichlorosilane as Si precursors on (110) Si is investigated. In the case of silane based processes Ge concentration is ~20% higher, whereas for dichlorosilane based processes it is ~30% lower on (110) Si compared to (100) Si. The morphology of the grown layers is found to be dependent on Ge concentration, layer thickness and process temperature. Use of optimized deposition parameters and adequate thickness results in high quality strained SiGe layers. Integration of high Ge content SiGe layers in multiple gate filed-effect transistor structures shows the expected differences in Ge content on the different Si planes forming Si fin. These differences can be avoided by adjusting the fin orientation on the Si wafer resulting in equal planes on the fin's top and sidewalls. When the investigated SiGe layers are incorporated in the buried channel field effect transistor structures on (110) Si wafers a significant thickening at the active windows edge is observed. It is speculated that this effect is connected with elastic SiGe relaxation caused by a non optimized process temperature.

Investigation of optical and chemical bond properties of hydrogenated amorphous silicon nitride for optoelectronics applications

The aim of this work is to determine optimal deposition parameters of silicon nitride for optical applications. The authors present the investigation of hydrogenated amorphous silicon nitride SiN x :H deposited by the low temperature PECVD method in high frequency reactors. The study of hydrogen bonds in the SiN x :H thin films were detailed. The impact of NH 3, SiH 4 and N 2 flow ratio and radio frequency power on optical coefficients in relation to chemical composition and roughness of the film is studied. The correlation between chemical bonds (N–H, Si–H) and refractive index and extinction coefficients is systematically verified. The experimental results show that the films with high refractive indexes superior to 2.05 and low roughness of about 0.35 nm can be achieved for optoelectronics applications by tuning the flow ratio or decreasing the RF power. A variety of processes have been suggested as compatible with low thermal budget (under 350 °C) in order to integrate optical waveguides with lower loss. In particular, the incorporation of N 2 as dilution gas is suited to the fabrication of SiN x :H films optical waveguide requiring low N–H bonds, low concentration of hydrogen [H] and high refractive index.

Two-Dimensional Arrays of Gold Nanoparticles for Plasmonic Nanosensor

Two dimensional (2D) arrays of noble metal nanoparticles are widely used in the sensing of nanoscale biological and chemical events. Research in this area has sparked considerable interest in many fields owing to the novel optical properties, e.g., the localized surface plasmon resonance, of these metallic nanoarrays. In this paper, we report successes in fabricating 2D arrays of gold nano-islands using nanosphere lithography. The reproducibility and the effectiveness of the nano-patterning method are tested by means of spin coating and capillary force deposition. We found that the capillary force deposition method was more effective for nanospheres with diameters greater than 600 nm, whereas the spin coating method works better for nanospheres with diameters less than 600 nm. The optimal deposition parameters for both methods were reported, showing about 80% reproducibility. In addition, we characterize gold nano-island arrays both geometrically with AFM as well as optically with UV-VIS spectrometry. The AFM images revealed that the obtained nano-arrays formed a hexagonal pattern of truncated tetrahedron nano-islands. The experimental and theoretical values of the geometric parameters were compared. The 2D gold nano-arrays showed strong LSPR in the absorption spectra. As the nano-islands increased in size, the LSPR absorption bands became red-shifted. Linear dependence of the plasmon absorption maximum on the size of the gold nano-islands was identified through the increment in the plasmon absorption maximum rate for a one nanometer increase in the characteristic length of the nano-islands. We found that the 2D gold nano-arrays showed nearly seven-fold higher sensitivity of the absorption spectrum to the size of the nano-islands as compared to colloidal gold nano-particles.

Sputtered amorphous silicon thin films for diode laser crystallization

Multicrystalline silicon thin films with large grains (100 μm) on glass are useful for thin film solar cells and for thin film transistors. These films can be prepared by diode laser irradiation of amorphous silicon films, which previously had been deposited by PECVD or electron beam evaporation. In this paper, the applicability of sputtered amorphous silicon thin films on glass for diode laser crystallization is investigated. For this process the sputter gas content in the films and their optical properties, particularly the absorption for the diode laser wavelength of 808 nm, are crucial. The sputtering parameters gas pressure and power are optimized for increasing the optical absorption and for decreasing the sputter gas incorporation. It is demonstrated that if using optimum deposition parameters diode laser crystallization leads to large grained multicrystalline silicon thin films. The crystallized layers show, different to previous results, a preferred (100)-orientation.

Characterization and optimization of indium tin oxide films for heterojunction solar cells

Well suited and reliable values of the optical and electrical properties of thin indium tin oxide (ITO) films are needed in order to choose the optimal deposition parameters and to perform reliable modeling for solar cells design. In this work, a new method will be presented to evaluate the ITO transparency directly on silicon substrates. The effects of each deposition parameter that influences the ITO transparency and conductivity force a trade-off in the frame of values useful for SHJ solar cells. The deposition of our optimized ITO film on a textured wafer yields a weighted average reflectance as low as 4.4±0.2%. The deposition of an MgF 2/ITO double-layer anti-reflection coating (DL-ARC) on textured cells increases the efficiency from 17.9%, measured immediately after contacts have been added to the ITO, to 18.4% after the MgF 2 deposition. An annealing step at 200 °C for 10 min proved to further increase the efficiency up to 18.9%, for a total gain of 1%.

Fabrication of Y 2O 3-doped BaZrO 3 thin films by electrostatic spray deposition

Electrostatic spray deposition (ESD) technique was used to fabricate dense Y 2O 3-doped BaZrO 3 (BYZ) thin films, which have been extensively studied for the protonic ceramic fuel cell electrolyte. Effects of the ESD process parameters (i.e. substrate temperature, type of precursor, flow rate and applied voltage) on the microstructure of as-deposited films were studied. The uniform as-deposited films were obtained using a mixture of zirconium acetylacetonate, barium chloride dihydrate and yttrium chloride hexahydrate precursors in a solvent mixture of butyl carbitol and deionized water at a volume ratio of 50:50. The optimum deposition parameters were obtained at the substrate temperature of 250 °C with the applied voltage and flow rate in a range of 10–12 kV and 1.4–2.8 ml/h, respectively. The as-deposited films were subsequently annealed at 1350 °C for 10 h to ensure the complete chemical reactions of the precursors. X-ray diffraction patterns reveal the perovskite structures of the annealed BYZ films (deposited on yttria stabilized zirconia substrates) with only traces of Y 2O 3 phase, which could arise from the loss of BaO at high annealing temperatures.

Optimization of parameters for deposition of Ga-doped ZnO films by DC reactive magnetron sputtering using Taguchi method

Ga-doped ZnO (ZnO:Ga) transparent conductive films were deposited on glass substrates by DC reactive magnetron sputtering. Taguchi method was used to find the optimal deposition parameters including oxygen partial pressure, argon partial pressure, substrate temperature, and sputtering power. By employing the analysis of variance, we found that the oxygen and argon partial pressures were the most influencing parameters on the electrical properties of ZnO:Ga films. Under the optimized deposition conditions, the ZnO:Ga films showed acceptable crystal quality, lowest electrical resistivity of 2.61 × 10 −4 Ω cm, and high transmittance of 90% in the visible region.

Hydroxyapatite coatings prepared by a high power laminar plasma jet

For two hydroxyapatite (HA) powders, containing particles differing in mass by a factor of 20, a set of optimum deposition parameters was defined, leading to the coatings with high crystallinity (80–90%), high adhesion strength (60 and 40MPa for the coating thicknesses of 120μm and 350μm, respectively) and excellent microstructure (coatings were without micro- or macro-cracks, without delaminating on substrate-coating surface contact, and possess low porosity, 1–2%). It was shown that higher plasma power (52kW) did not necessarily lead to a higher HA decomposition.

Growth and structural characterization of epitaxial Cu/Nb multilayers

Electron beam evaporation with optimized deposition parameters has been used to grow good quality epitaxial Cu/Nb nanoscale multilayered films on sapphire substrates. The quality of the epitaxial films, as measured by the intensities and widths of the X-ray diffraction peaks, increases with increasing deposition temperature. However, high deposition temperatures also enhance the tendency for layer pinch-off which eventually leads to spheroidization and growth of multilayer films with polycrystalline islands. Deposition temperatures and rates were optimized to produce the highest quality epitaxial films with continuous nanolayers, suitable for in situ deformation experiments in a synchrotron-based Laue micro-diffraction set up.

Nickel–lithium oxide alloy transparent conducting films deposited by spray pyrolysis technique

In this research, nickel oxide (NiO) transparent semiconducting films are prepared by spray pyrolysis technique on glass substrates. The effect of Ni concentration in initial solution and substrate temperature on the structural, electrical, thermoelectrical, optical and photoconductivity properties of NiO thin films are studied. The results of investigations show that optimum Ni concentration and suitable substrate temperature for preparation of basic undoped NiO thin films with p-type conductivity and high optical transparency is 0.1 M and 450 °C, respectively. Then, by using these optimized deposition parameters, nickel–lithium oxide ((Li:Ni)O x ) alloy films are prepared. The XRD structural analysis indicate the formation of the cubic structure of NiO and (Li:Ni)O x alloy films. Also, in high Li doping levels, Ni 2O 3 and NiCl 2 phases are observed. The electrical measurements show that the resistance of the films decreases with increasing Li level up to 50 at%. For these films, the optical band gap and carrier concentration are obtained to be 3.6 eV and 10 15–10 18 cm −3, respectively.

Novel Multiparametric Approach to Elucidate the Surface Amine-Silanization Reaction Profile on Fluorescent Silica Nanoparticles

This Article addresses the important issue of the characterization of surface functional groups for optical bioassay applications. We use a model system consisting of spherical dye-doped silica nanoparticles (NPs) that have been functionalized with amine groups whereby the encapsulated cyanine-based near-infrared dye fluorescence acts as a probe of the NP surface environment. This facilitates the identification of the optimum deposition parameters for the formation of a stable ordered amine monolayer and also elucidates the functionalization profile of the amine-silanization process. Specifically, we use a novel approach where the techniques of fluorescence correlation spectroscopy (FCS) and fluorescence lifetime measurement (FL) are used in conjunction with the more conventional analytical techniques of zeta potential measurement and Fourier transfer infrared spectroscopy (FTIR). The dynamics of the ordering of the amine layer in different stages of the reaction have been characterized by FTIR, FL, and FCS. The results indicate an optimum reaction time for the formation of a stable amine layer, which is optimized for further biomolecular conjugation, whereas extended reaction times lead to a disordered cross-linked layer. The results have been validated using an immunoglobulin (IgG) plate-based direct binding assay where the maximum number of IgG-conjugated aminated NPs were captured by immobilized anti-IgG antibodies for the NP sample corresponding to the optimized amine-silanization condition. Importantly, these results point to the potential of FCS and FL as useful analytical tools in diverse fields such as characterization of surface functionalization.

The influence of deposition temperature on vanadium dioxide thin films microstructure and physical properties

Vanadium dioxide thin films were successfully prepared on soda lime glass substrates using the optimised conditions for r.f-inverted cylindrical magnetron sputtering. The optimised deposition parameters were fixed and then a systematic study of the effect of deposition temperature, ranging from 450 °C to 550 °C, on the microstructure of thermochromic thin films was carried out. The deposited films were found to be well crystallised, showing strong texture corresponding to the (011) plane, indicating the presence of vanadium dioxide.

Effects of rapid thermal annealing treatment on 0·95(Na0·5Bi0·5)TiO3-0·05BaTiO3 thin films

A 0·95(Na0·5Bi0·5)TiO3-0·05BaTiO3+1 wt-%Bi2O3 (NBT-BT3) ceramic was used as target to deposit the NBT-BT3 thin films. The excess 1 wt-%Bi2O3 was used to compensate the vapourisation of Bi2O3 during the depositing processes. The optimal deposition parameters were substrate temperature of 500°C, radio frequency power of 100 W, chamber pressure of 10 mtorr and oxygen concentration of 40%. Rapid thermal annealing treated processes were carried out on NBT-BT3 thin films from 600 to 800°C in ambient or in oxygen atmosphere for 1 min. The surface morphologies and thicknesses of NBT-BT3 thin films were characterised by field emission scanning electron microscopy, and the thickness was ∼216 nm. It would be shown that the NBT-BT3 thin films annealed in oxygen atmosphere had the smaller grain size, larger memory window, smaller leakage current density, larger remanent and saturation polarisation and smaller coercive field than the NBT-BT3 thin films annealed in ambient atmosphere.