Increasing Deposition Temperature Research Articles

Influence of process parameters on atomic layer deposition of ZrO2 thin films from CpZr(NMe2)3 and H2O

Atomic layer deposition of ZrO2 films from tris(dimethylamino)cyclopentadienylzirconium CpZr(NMe2)3 and H2O, was investigated using real-time characterization of the growth process and post-growth measurements of the films. Self-limited nature of the deposition process was observed at substrate temperatures ranging from 120 to 350°C. In this temperature range growth rate of 0.08–0.1nm per cycle was obtained on silicon substrates. The films deposited on silicon substrates at 200°C and higher temperatures contained tetragonal and monoclinic phases of ZrO2. The phase composition of the films depended on the deposition temperature as well as on the film thickness. The concentration of carbon residues decreased with increasing deposition temperature and did not exceed 0.9at.% in the films deposited at 250°C and higher temperatures. The refractive indices and densities of films grown from CpZr(NMe2)3 and H2O at 250–350°C ranged from 2.15 to 2.20 (at a wavelength of 633nm) and 5.6 to 6.0g/cm3, respectively, being close to the highest values obtained for films deposited from ZrCl4 and H2O. The former process ensured, however, more uniform nucleation of ZrO2 on graphene than the latter process did.

Optical properties of (1 0 0) oriented ZnO:Gd films deposited by reactive radio frequency magnetron sputtering

ZnO:Gd films with (100) preferred orientation were deposited on glass substrates by reactive radio frequency magnetron sputtering with the deposition temperature of 100–500°C. The (100) texture of the ZnO:Gd film is enhanced with the increase of deposition temperature. The average transmittance of the ZnO:Gd films in the visible region is over 83% and the film deposited at 500°C exhibits the highest transmittance (90%). The optical band gap of the ZnO:Gd films increases from 3.213 to 3.227eV as the deposition temperature increases. The structural defects induced by Gd doping lead to the weak band gap related emission and the strong defects related emissions of the films.

Effect of deposition temperature on electron-beam evaporated polycrystalline silicon thin-film and crystallized by diode laser

The effects of the deposition temperature on the microstructure, crystallographic orientation, and electrical properties of a 10-μm thick evaporated Si thin-film deposited on glass and crystallized using a diode laser, are investigated. The crystallization of the Si thin-film is initiated at a deposition temperature between 450 and 550 °C, and the predominant (110) orientation in the normal direction is found. Pole figure maps confirm that all films have a fiber texture and that it becomes stronger with increasing deposition temperature. Diode laser crystallization is performed, resulting in the formation of lateral grains along the laser scan direction. The laser power required to form lateral grains is higher in case of films deposited below 450 °C for all scan speeds. Pole figure maps show 75% occupancies of the (110) orientation in the normal direction when the laser crystallized film is deposited above 550 °C. A higher density of grain boundaries is obtained when the laser crystallized film is deposited below 450 °C, which limits the solar cell performance by n = 2 recombination, and a performance degradation is expected due to severe shunting.

Electronic structure of V2O3 thin film prepared by RF magnetron sputtering using oxygen radical and V-metal

We have prepared V2O3 thin films on Al2O3 (0001) substrate by RF magnetron sputtering using oxygen radical and V-metal target, and studied their electronic structures by X-ray absorption spectroscopy (XAS) and X-ray photoemission spectroscopy (XPS). The as-deposited V2O3 thin films deposited at 600 °C exhibits high crystallization by oxygen radical irradiation during deposition. The electrical resistivity decreases with increasing deposition temperature, and this result is due to decreasing electron scattering. The crystal field splitting (10Dq) of the V2O3 thin film estimated from the fitting of the V 2p XAS spectrum is larger than that of the bulk crystal. In the XPS spectrum of the valence band region, the density of state (DOS) of the orbital in the V 3d state increases at around the Fermi level. These results contribute to the lattice distortion between the thin film and the substrate.

Structurally tailored Cu(InxGa1 − x) Se2 thin films via RF magnetron sputtering

Cu(InxGa1−x) Se2 (CIGS) thin films were deposited onto soda-lime glass substrates with Mo coating via the one step radio frequency (RF) magnetron sputtering without a post-selenization process at the substrate temperature varying from 550°C to 630°C. The effect of deposition temperature on the structural properties of CIGS thin films has been characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). It was found that an increased deposition temperature of up to 580°C contributes to produce the smooth surface, large grain size, and increased crystallinity of the thin films. But further increased deposition temperature results in a decrease in smoothness and an increase in grain size. The optimized temperature (580°C) shows the best effect on the composition and formation of the chalcopyrite structure without impurities.

Growth and electrical properties of in situ phosphorus-doped polycrystalline silicon films using Si3H8 and PH3

In situ phosphorus-doped polycrystalline silicon (polysilicon) films grown on silicon oxide layers using trisilane (Si3H8) and phosphine (PH3) as precursors are investigated as a function of the Si3H8/PH3 gas flow ratio and the growth temperature. At a high flow rate for Si3H8 in the temperature range of 600–700 °C, the deposition process is controlled by the rate of desorption of hydrogen molecules on the surface, which has an activation energy of 1.13 eV. For a low Si3H8 flow rate at growth temperatures >650 °C, however, the deposition is limited by the diffusion of Si3H8 gas to the surface. The presence of phosphorus decreases the crystallization temperature of the polysilicon layers during growth. In addition, the ratio of phosphorus incorporated into the polysilicon decreases with increasing growth temperature because of the increase in the growth rate. The resistivity of the phosphorus-doped polysilicon films decreases with increasing deposition temperature at the same phosphorus concentration, indicating that the use of a high growth temperature results in an enhancement in the activation of phosphorus in the polysilicon films during growth.

Effect of deposition temperature on the properties of ZnO-doped indium oxide thin films

ZnO-doped In2O3 (ZIO) thin films were deposited on quartz substrates at various deposition temperatures by radio-frequency magnetron sputtering. All the ZIO thin films showed a significant dependence on the deposition temperature. A strong preferential growth orientation was observed for all samples except the one deposited at 25 °C. As the deposition temperature was increased, the crystalline orientation of the main (222) plane did not change, but the full width at half maximum got smaller and the intensity increased rapidly. The ZIO thin film deposited at 100 °C showed the highest figure of merit with an average particle size of 60 nm, a bandgap energy of 3.51 eV, an electrical resistivity of 2.63 × 10−3 Ωcm, and an electron concentration of 4.99 × 1020 cm−3. A blue-shift of optical bandgap enegy was observed with increasing deposition temperature. These results suggest that the optimum deposition temperature for growing high-quality ZIO films is 100 °C and that the structural, optical, and electrical properties of ZIO thin films can be modulated by controlling the deposition temperature.

Effect of Deposition Temperature on Some Properties of MOCVD Molybdenum Sulphide Thin Films

Molybdenum sulphide thin films were deposited on sodalime glass, silicon wafer and stainless steel (AISI 304L) substrates using Metal Organic Chemical Vapour Deposition (MOCVD) technique at temperatures ranging from 360 o C to 450 o C. The films were characterized using Rutherford Backscattering Spectroscopy (RBS), Ultraviolet-Visible Spectroscopy, Four point probe technique, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Elemental analysis showed that the S/Mo ratio increases from 1.22 to 2.33 with increasing temperature. The optical band gap varies from 1.69 eV to 1.79 eV as deposition temperature increases. The electrical conductivity ranging from 0.5 Ω -1 cm -1 to 1.30 Ω -1 cm -1 also depends on deposition temperature. SEM micrographs of the films showed the layered structure of the film with an estimated grain size that increases from 1.6 µm to 2.4 µm as the deposition temperature increases. This study demonstrates that the properties of the films depend on the deposition temperature.

Defect studies of thin ZnO films prepared by pulsed laser deposition

Thin ZnO films were grown by pulsed laser deposition on four different substrates: sapphire (0 0 0 1), MgO (1 0 0), fused silica and nanocrystalline synthetic diamond. Defect studies by slow positron implantation spectroscopy (SPIS) revealed significantly higher concentration of defects in the studied films when compared to a bulk ZnO single crystal. The concentration of defects in the films deposited on single crystal sapphire and MgO substrates is higher than in the films deposited on amorphous fused silica substrate and nanocrystalline synthetic diamond. Furthermore, the effect of deposition temperature on film quality was investigated in ZnO films deposited on synthetic diamond substrates. Defect studies performed by SPIS revealed that the concentration of defects firstly decreases with increasing deposition temperature, but at too high deposition temperatures it increases again. The lowest concentration of defects was found in the film deposited at 450° C.

Effect of growth temperature on the epitaxial growth of ZnO on GaN by ALD

We report on the epitaxial growth of ZnO on GaN template by atomic layer deposition (ALD). Diethylzinc (DEZn) and water vapour (H2O) were used as precursors. The structure and the quality of the grown ZnO layers were studied with scanning electron microscope (SEM), X-ray diffraction (XRD), photoluminescence (PL) measurements and positron annihilation spectroscopy. The ZnO films were confirmed epitaxial, and the film quality was found to improve with increasing deposition temperature in the vicinity of the threshold temperature of two dimensional growth. We conclude that high quality ZnO thin films can be grown by ALD. Interestingly only separate Zn-vacancies were observed in the films, although ZnO thin films typically contain fairly high density of surface pits and vacancy clusters.

Structural and dynamical magnetic response of co-sputtered Co2FeAl heusler alloy thin films grown at different substrate temperatures

The interdependence between the dynamical magnetic response and the microstructural properties such as crystallinity, lateral crystallite size, structural ordering of the co-sputtered polycrystalline Co2FeAl thin films on Si (100) are studied by varying the growth temperature from room temperature (RT) to 600 °C. Frequency (7–11 GHz) dependent in-plane ferromagnetic resonance (FMR) studies were carried out by using co-planar waveguide to estimate Gilbert damping constant (α) and effective saturation magnetization (4πMeff). The improvement in crystallinity, larger crystallite and particle sizes of the films are critical in obtaining films with lower α and higher 4πMeff. Increase in the lattice constant with substrate temperature indicates the improvement in the structural ordering at higher temperatures. Minimum value of α is found to be 0.005 ± 0.0003 for the film deposited at 500 °C, which is comparable to the values reported for epitaxial Co2FeAl films. The value of 4πMeff is found to increase from 1.32 to 1.51 T with the increase in deposition temperature from RT to 500 °C. The study also shows that the root mean square (rms) roughness linearly affects the FMR in-homogenous line broadening and the anisotropy field.

Characterization of Al2O3 thin films fabricated through atomic layer deposition on polymeric substrates

This paper reports on the fabrication of good quality Al2O3 thin films on flexible substrates including polyethylene naphthalate (PEN), polyethylene terephthalate (PET) and Polyamide at different temperatures down to 50 °C under very short water purging steps of 10 s. Al2O3 films with appreciable growth rates having good morphological, chemical, electrical and optical characteristics have been produced. Growth rates of 1.16, 1.14 and 1.15 A/cycle have been observed at 50 °C for PET, PEN and polyamide substrates respectively. The surface morphology has been improved with the increase in deposition temperature. Low average arithmetic roughness of 0.88 and 0.78 nm have been recorded for the Al2O3 films deposited at 150 °C on PEN and polyamide respectively. The XPS analysis confirmed the fabrication of Al2O3 films without any carbon contamination and Al 2p, Al 2s and O 1s peaks were appeared at binding energies of 74, 119 and 531 eV, respectively. Excellent insulating properties were observed for the Al2O3 films and optical transmittance of more than 85 % was recorded in the visible region. The experimental results suggest that polymeric materials are excellent candidates to be used as substrates in the fabrication of Al2O3 thin films through atomic layer deposition.

Stress reduction in ultra-small thin film Al2O3 diaphragms by atomic layer deposition

In this paper we present a concept of reducing the residual stress in atomic-layer-deposited Al2O3 diaphragms by compensating the tensile intrinsic stress with a compressive thermal stress. This is facilitated by using single-crystal quartz substrates which exhibit a high coefficient of thermal expansion. We studied the stress in diaphragms fabricated at different deposition temperatures and showed that there is a transition from tensile to compressive residual stress with increasing deposition temperature. An optimal temperature for stress-free films was proposed and diaphragms with a compressive residual stress as small as −10MPa were fabricated.

Effect of laser wavelength on phase and microstructure of TiO2 films prepared by laser chemical vapor deposition

Rutile and anatase TiO2 films were prepared by laser chemical vapor deposition using CO2 and Nd:YAG lasers. The effects of laser wavelength on the phase, orientation, and microstructure of these TiO2 films were investigated. Using a CO2 laser, single-phase rutile TiO2 films were obtained at 826–1225K. These films showed a (100) orientation and a dense structure. The highest deposition rate was 83μmh−1 at 1070K. Using a Nd:YAG laser, the phase of the TiO2 films changed from rutile to anatase with increasing deposition temperature from 852 to 1230K. The rutile TiO2 films showed a (100) orientation with a columnar structure, while the anatase TiO2 films exhibited a (001) orientation with a cauliflower-like structure. Using a Nd:YAG laser, the highest deposition rates for rutile and anatase TiO2 films were 142 and 40μmh−1, respectively.

Zinc vacancy mediated structural phase transition and photoluminescence in nanocrystalline ZnS thin films

Nanocrystalline thin films of zinc sulphide were prepared on glass substrate at various deposition temperatures by thermal evaporation technique. The variation of the structural and optical properties of films deposited at various substrate temperatures was investigated in detailed. X-ray diffraction spectra showed that films deposited at 300 and 400 °C are polycrystalline in nature having cubic and both cubic and wurtzite structure, respectively. However, film deposited at temperature of 200 °C was found to be amorphous in nature. The ultra-violet and visible absorption studies showed that the band gap of films increases with increase in deposition temperatures. Photoluminescence spectra displayed emission near 396 and 444 nm, which arises due to zinc vacancies and sulphur vacancies, respectively and has been correlated to phase transition of the films.

DC electrical conductivity study of amorphous carbon nitride films prepared by reactive RF magnetron sputtering

The effects of chemical bonding states on the electrical properties of hydrogen-free amorphous carbon nitride (a-CNx) films were reported. a-CNx films were prepared by reactive RF magnetron sputtering at various deposition temperatures. The electrical conductivity of the a-CNx films increased with increasing deposition temperature because of the predominant sp2C–C bonding sites. Their conductivity increased by almost one order of magnitude with a 25% decrease in the fraction of the N-sp3C bonding state. It was found that the fraction of the N-sp2C bonding state strongly contributed to the increase in the electrical conductivity. Nitrogen incorporation led to an increase in the sp3C–C bonding fraction in the films; as a result, the conductivity of the a-CNx films was found to be lower than that of the a-C films deposited under the same conditions.

Plasma-Sprayed Y2O3-Stabilized ZrO2 Electrolyte With Improved Interlamellar Bonding for Direct Application to Solid Oxide Fuel Cells

Atmospheric plasma spraying was employed to prepare anode, cathode, and Y2O3-stabilized ZrO2 (YSZ) electrolyte to aim at reducing manufacturing cost. YSZ electrolytes were deposited on the anode at different deposition temperatures of 200 °C, 400 °C and 600 °C to optimize the gas tightness of plasma-sprayed YSZ electrolyte. The influences of the deposition temperature on the microstructure and gas-tightness of plasma-sprayed YSZ electrolyte were investigated. The effect of microstructure and the gas-tightness of YSZ electrolyte on the open circuit voltage and the output performance of solid oxide fuel cells (SOFCs) were examined. The results showed with the increase of deposition temperature, the porosity of YSZ electrolytes almost decreased by about 80% and the microstructure of YSZ electrolytes changed from the typical lamellar structure to the continuous columnar crystal structure. At a deposition temperature of 600 °C the gas permeability decreased to 1.5 × 10−7 cm4gf−1s−1, and the highest open circuit voltage can reach 1.026 V, indicating the applicability of the as-sprayed YSZ directly to the SOFC electrolyte.

Effect of deposition temperature on the alignment of hexagonal laminates in turbostratic boron nitride thin film

The deposition behavior of turbostratic boron nitride (t-BN) films was investigated with the focus on its microstructure variation in relation to deposition temperature substrate bias voltage. BN films were deposited using the unbalanced magnetron sputtering method. Thin (100μm) Si strips (3×40mm2) coated with a nanocrystalline diamond thin layer were used as substrates. A BN target was used, which was connected to a radio frequency power supply set at 400W. A pulsed direct current power supply connected to a substrate holder was used for negative biasing. The deposition pressure was 0.27Pa with a flow of Ar (18sccm)–N2 (2sccm) mixed gas. Only t-BN films were deposited with the substrate bias less than −100V irrespective of the deposition temperature. The orientation of (0002) t-BN laminate alignment changed from normal to parallel to the substrate surface with increased deposition temperature. High resolution transmission electron microscopy and Fourier transform infrared spectroscopy confirmed such behavior. However, the application of bias voltage made the (0002) laminates align normal to the substrate surface even at high deposition temperatures. The films tended to react with moisture in an ambient atmosphere as confirmed by the appearance of OH absorption peak in the FTIR spectrum. The measured OH absorption intensity was not influenced by the variation of deposition variables.

Detailed Raman Study of DLC Coating on Si (100) Made by RF-PECVD

Radio frequency (RF) plasma enhanced chemical vapour deposition (PECVD) technique was used to make a diamond like carbon (DLC) coating on silicon (100) substrate. The deposition was carried out using C2H2 as the process gas, at different temperatures, 25°C (room temperature) and 300°C with constant power and flow rate. Characterization techniques such as ellipsometry and Raman spectroscopy were used to characterize these samples. Raman analysis of DLC coatings at different temperature is carried out in detail for two different excitation wavelengths i.e. 514 and 785nm and, results are presented in the paper. Blue-shiftis observed in both D and G peaks of Raman spectrum with increase in deposition temperature, which indicates the formation of compressive strain in high temperature deposited DLC coatings. Dispersion in both D and G peaks is observed for different excitation wavelength suggesting that the coating is hydrogenated DLC. The degree of hydrogenation of the DLC coating appears to decrease with respect to the deposition temperature. Nano-indentation study shows a marginal increase in hardness with increase in deposition temperature.

Effects of Deposition Temperature on the Electrochemical Deposition of Zinc Oxide Thin Films from a Chloride Solution

The structural, electrical, and optical properties of ZnO thin films electrochemically deposited from a chloride solution are investigated. We focus on deposition temperatures. The band gap energy decreased from 3.50 to 3.44eV as deposition temperatures increased from 60 to 80°C. This variation of band gap is discussed with respect to both conduction and valence band shifts, and the Burstein-Moss effect caused by numerous carriers. Increase in the carrier density of ZnO thin films was observed with increasing deposition temperature; a markedly-high carrier density of 1 © 10 21 cm ¹3 was exhibited. The origin of the carrier density was also investigated. Although the Cl ¹ content in ZnO thin films decreased with increasing deposition temperature, the increase of Cl ¹ acting as a donor was indicated. [doi:10.2320/matertrans.M2013386]