Effect Of Deposition Pressure Research Articles

Effect of oxygen pressure on preferred deposition orientations and optical properties of cubic MgZnO thin films on amorphous quartz substrate

Cubic MgZnO thin films were deposited on amorphous quartz substrate by PLD method. Effect of deposition pressure on preferential orientation and optical absorption characteristics of MgZnO thin films were studied. The preferred orientation of cubic MgZnO changed from (200) to (111) when deposition pressure increased, and absorption edges of which shift to longer wavelength direction because Mg content of MgZnO thin film decreased. Cubic MgZnO showed much better crystal quality and preferential orientation growth characteristics on proper crystal substrate, because on this substrate the preferred orientation of cubic MgZnO is accordance with that grown in free growth mode on amorphous substrate at special air pressure.

Effects of Deposition Pressure on the Microstructure and Hardness of Ti/TiN Nanolayered Coatings

The polycrystalline Ti/TiN multilayer films were deposited by magnetron sputtering. We investigated the effects of mixed discharge gas pressure on the microstructural, interfacial, and mechanical properties of the polycrystalline Ti/TiN multilayer films. X-ray reflectivity and diffraction (XRR and XRD), and nanoindentation were used to characterize the structures and mechanical properties for the films. It was found that the hardness enhancement is caused by the modulus difference in the interface between layer Ti and TiN. The elastic modulus is strongly related to the composition of crystalline orientation and distortion. The sharp interface is good for improving the mechanical properties for Ti/TiN multilayer.

Electro- and opto-resistive switching behaviors of the Nb doped SrTiO3 films

Nb doped SrTiO3 (Nb:STO) films were deposited on (100) SrTiO3 substrates using a pulse laser deposition technique. The effects of deposition pressure on their structural, electrical and optical properties were investigated. Decrease in deposition pressure lead to decrease in grain size and average surface roughness. Various optical parameters such as refractive index, extinction coefficient, and band gap were calculated by applying the envelop or extrapolation methods using the transmittance data obtained from a UV/Vis spectrophotometer. A systematic decrease in resistivity and increment of negative charged carriers was observed with decreasing deposition pressure. Experimental results exhibited electro- and opto-resistive switching behaviors with a resistive transition from high resistance state to low resistance state on the application of current-pulse or UV light. Multi-level resistance states have also been demonstrated using a train of current pulses of different magnitudes or a simultaneous application of current and UV light. Such observed phenomenon makes Nb:STO a potential candidate to be used in future for the fabrication of multi-level memory devices and transparent thin films transistors.

Pressure dependent structural and optical properties of silicon carbide thin films deposited by hot wire chemical vapor deposition from pure silane and methane gases

Silicon carbide (SiC) thin films were deposited using hot wire chemical vapor deposition technique from silane (SiH4) and methane (CH4) gas precursors. The effect of deposition pressure on structural and optical properties of SiC films was investigated. Various spectroscopic methods including Fourier transform infrared spectroscopy, Raman scattering spectroscopy, Auger electron spectroscopy, and UV–Vis–NIR spectroscopy were used to study these properties. Films deposited at low deposition pressure were Si-rich, and were embedded with nano-crystals of silicon. These films showed strong absorption in the visible region and had low energy band gaps. Near stoichiometric SiC film, were formed at intermediate deposition pressure and these films were transparent in the visible region and exhibited a wide optical band gap. High deposition pressures caused inhomogeneity in the film as reflected by the increase in disorder parameter and low refractive index of the films. This was shown to be due to formation of sp 2 carbon clusters in the film structure.

Influence of RF magnetron sputtering conditions on the properties of transparent conductive gallium-doped magnesium zinc oxide thin films

Gallium-doped magnesium zinc oxide (GMZO) thin films were deposited onto glass substrates using RF magnetron sputtering using GMZO ceramic targets under different sputtering conditions. The substrate temperature and deposition pressure effects on the structural, electrical and optical properties of the GMZO thin film were investigated. Transparent conductive GMZO thin films were demonstrated in this study to possess a wurtzite structure, average transmittance above 80% in the 400nm and 800nm wavelength range with a low resistivity of 1.62×10−3Ωcm when deposited onto glass substrates using RF magnetron sputtering.

Room-Temperature Deposition of Silicon Thin Films by RF Magnetron Sputtering

Silicon thin film was successfully deposited on glass substrate using Radio frequency (RF) magnetron sputtering. The effect of deposition pressure on the physical and structural properties of thin films on the glass substrate was studied. The film thickness and deposition rate decreased with decreasing deposition pressure. Field emission scanning electron microscopy (FESEM) shows as the deposition pressure increased, the surface morphology transform from concise structured to not closely pack on the surface. Raman spectroscopy result showed that the peak was around 508 cm-1, showing that the thin film is nanocrystalline instead of polycrystalline silicon.

Amorphous Silicon Carbide Thin Films Deposited by Magnetron Co-Sputtering: Effect of Applied Power and Deposition Pressure on Film Characteristics

In this work, the effect of deposition pressure and total power applied to Si and C targets on the a-SiC film characteristics was investigated by profilometry, X-ray diffraction (XRD), Raman spectroscopy, and Rutherford-Backscattering Spectrometry (RBS). Profilometry results indicate an increase in the film thickness by increasing both the deposition pressure and total power. Both Crich and Si-rich a-SiC films were grown only by varying the deposition pressure or total power. Raman spectra suggest that the films contain amorphous phases because a-SiC clusters together with a-Si and a-C clusters were observed. The XRD analysis confirmed the amorphous structure of these films.

Properties of TiO₂Thin Films Deposited on PET Substrate for High Energy Density Capacitor

thin films for high energy density capacitors were prepared by r.f. magnetron sputtering at room temperature. Flexible PET (Polyethylene terephtalate) substrate was used to maintain the structure of the commercial film capacitors. The effects of deposition pressure on the crystallization and electrical properties of films were investigated. The crystal structure of films deposited on PET substrate at room temperature was unrelated to deposition pressure and showed an amorphous structure unlike that of films on Si substrate. The grain size and surface roughness of films decreased with increasing deposition pressure due to the difference of mean free path. X-ray photoelectron spectroscopy (XPS) analysis revealed the formation of chemically stable films. The dielectric constant of films was significantly changed with deposition pressure. films deposited at low pressure showed high dissipation factor due to the surface microstructure. The dielectric constant and dissipation factor of films deposited at 70 mTorr were found to be 100~120 and 0.83 at 1 kHz, respectively. The temperature dependence of the capacitance of films showed the properties of class I ceramic capacitors. films deposited at 10~30 mTorr showed dielectric breakdown at applied voltage of 7 V. However, the films of 500~300 nm thickness deposited at 50 and 70 mTorr showed a leakage current of A at 100 V.

Influence of boron carbide on properties of CVD-diamond thin films at various deposition pressures

Microcrystalline boron-doped diamond (BDD) films are synthesized on the silicon substrate by the hot-filament chemical vapor deposition method under the gas mixture of hydrogen and methane in the presence of boron carbide (B4C) placed in front of filaments. The observed results of scanning electron microscopy, Raman spectroscopy and X-ray diffraction show the morphologies. Microstructures for various deposition pressures of as-grown diamond films are found to be dependent on the change of deposition pressure. These results reveal that with the increase of deposition pressure, resistivity decreases and increase in the grain size is noted in the presence of B4C. Resistivity shows a sudden fall of about three orders of magnitude by the addition of boron in the diamond films. This is due to the crystal integrity induced by B-atoms in the structure of diamond in the presence of B4C. These results are also significant for the conventional applications of BDD materials. The effects of deposition pressure on the overall films morphology and the doping level dependence of the diamond films have also been discussed.

Effect of deposition pressure on structural, optical and electrical properties of zinc selenide thin films

ZnSe thin films have been prepared by inert gas condensation method at different gas pressures. The influence of deposition pressure, on structural, optical and electrical properties of polycrystalline ZnSe films have been investigated using X-ray diffraction (XRD), optical transmission and conductivity measurements. The X-ray diffraction study reveals the sphalerite cubic structure of the ZnSe films oriented along the (111) direction. The structural parameters such as particle size [6.65–22.24nm], strain [4.01–46.6×10−3lin−2m−4] and dislocation density [4.762–18.57×1015linm−2] have been evaluated. Optical transmittance measurements indicate the existence of direct allowed optical transition with a corresponding energy gap in the range 2.60–3.00eV. The dark conductivity (σd) and photoconductivity (σph) measurements, in the temperature range 253–358K, indicate that the conduction in these materials is through an activated process having two activation energies. σd and σph values decrease with the decrease in the crystallite size. The values of carrier life time have been calculated and are found to decrease with the reduction in the particle size. The conduction mechanism in present samples has been explained, and the density of surface states [9.84–21.4×1013cm−2] and impurity concentration [4.66–31.80×1019cm−3] have also been calculated.

Multi-phase structured silicon carbon nitride thin films prepared by hot-wire chemical vapour deposition

In this work, Silicon Carbon Nitride (Si–C–N) thin films were deposited by Hot Wire Chemical Vapour Deposition (HWCVD) technique from a gas mixture of silane (SiH 4), methane (CH 4) and nitrogen (N 2). Six sets of Si–C–N thin films were produced and studied. The component gas flow rate ratio (SiH 4:CH 4:N 2) was kept constant for all film samples. The total gas flow-rate (SiH 4 + CH 4 + N 2) was changed for each set of films resulting in different total gas pressure which represented the deposition pressure for each of these films ranging from 40 to 100 Pa. The effects of deposition pressure on the chemical bonding, elemental composition and optical properties of the Si–C–N were studied using Fourier transform infrared (FTIR) spectroscopy, Auger Electron Spectroscopy (AES) and optical transmission spectroscopy respectively. This work shows that the films are silicon rich and multi-phase in structure showing significant presence of hydrogenated amorphous silicon (a-Si:H) phase, amorphous silicon carbide (a-SiC), and amorphous silicon nitride (a-SiN) phases with Si–C being the most dominant. Below 85 Pa, carbon content is low, and the films are more a-Si:H like. At 85 Pa and above, the films become more Si–C like as carbon content is much higher and carbon incorporation influences the optical properties of the films. The properties clearly indicated that the films underwent a transition between two dominant phases and were dependent on pressure.

Aluminum doped silicon‐carbon alloys prepared by hot wire chemical vapor deposition

AbstractAluminum doped stoichiometric microcrystalline silicon carbide (µc‐SiC:H) thin films deposited by Hot Wire Chemical Vapor Deposition (HWCVD) technique have been studied. Without Al‐doping, highly crystalline µc‐SiC:H thin films prepared from monomethysilane (MMS) and hydrogen are mainly cubic polytype and are unintentionally doped into n‐type. Trimethyaluminum (TMAl) is used as a source of Aluminum. By increasing the TMAl/MMS ratio (rdoping), the dark conductivity of µc‐SiC:H thin film firstly decreases and then increases. This variation indicates the compensation from n‐type to p‐type, which is confirmed by the thermo‐power measurements. It is observed in the infrared spectra that the crystallinity of µc‐SiC:H thin film deceases with increasing rdoping. In order to improve the crystallinity of this conductive p‐type µc‐SiC:H thin film, the effect of deposition pressure (pdepo) has been investigated. With increasing pdepo, the crystallinity is improved and the structure of SiC alloys changes according to the Raman spectra. A maximum dark conductivity of 1.3×10–1 S/cm has been achieved at rdoping = 0.0620 and pdepo = 100 Pa. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Enhancement of electrical performance in In2O3 thin-film transistors by improving the densification and surface morphology of channel layers

We report on the fabrication of bottom-gate thin-film transistors (TFTs) using indium-oxide (In2O3) thin films as active channel layers. The films were deposited on thermally grown silicon dioxide (SiO2)/n-type silicon (Si) at room temperature (RT) by radio-frequency (RF) magnetron sputtering. The effect of deposition pressure on the performance of In2O3-TFTs was investigated in detail. A significant improvement of the device performance was observed for In2O3-TFTs with the decrease of the working pressure, which is attributed to enhanced densification, better surface morphology of the In2O3 channel layers prepared at lower deposition pressure. The fabricated TFT with optimal device performance exhibited a field-effect mobility (μFE) of 31.6cm2V−1s−1, a drain current on/off ratio of ∼107, a low off drain current of about 10−10A and a threshold voltage of 7.8V. Good device performance and low processing temperature make the In2O3-TFTs suitable for the potential applications in the transparent electronics.

Effects of Deposition Pressure on the Phase Formation and Electrical Properties of BiFeO3 Films Deposited by Sputtering

<TEX>$BiFeO_3$</TEX> (BFO) thin films were prepared on <TEX>$Pt/TiO_2/Si$</TEX> substrate by r.f. magnetron sputtering. The effects of deposition pressure on electrical properties were investigated using measurement of dielectric properties, leakage current and polarization. When BFO targets were prepared, Fe atoms were substituted with Mn 0.05% to increase electrical resistivity of films. (Fe+Mn)/Bi ratio of BFO thin films increases with increasing partial pressure of <TEX>$O_2$</TEX> gas. The deposited films showed the only BFO phase at 10 mTorr, the coexistence of BFO and <TEX>$Bi_2O_3$</TEX> phase at 30-50 mTorr, and the only <TEX>$Bi_2O_3$</TEX> phase at 70 mTorr. The crystallinity of BFO films was reduced due to the higher Bi contents and the decrease of surface mobility of atoms at high temperature. The porosity and surface roughness of films increased with the increase of the deposition pressure. The films deposited at high pressure showed low dielectric constant and high leakage current. The dielectric constant of films deposited at various deposition pressures was 84<TEX>${\sim}$</TEX>153 at 1 kHz. The leakage current density of the films deposited at 10<TEX>${\sim}$</TEX>70 mTorr was about <TEX>$7{\times}10.6{\sim}1.5{\times}10.2A/cm^2$</TEX> at 100 kV/cm. The leakage current was found to be closely related to the morphology and composition of the BFO films. BFO films showed poor P-E hysteresis loops due to high leakage current.

Preparation of ZnMgO:Ga thin films on flexible substrates by pulsed laser deposition

Transparent conducting ZnMgO:Ga films were deposited on flexible PET substrates by pulsed laser deposition (PLD). Effects of deposition pressure and time on the structural, electrical and optical properties of ZnMgO:Ga films were investigated. The films showed a low resistivity about 7.68 × 10 −4 Ω cm when deposited at the pressure of 0.03 Pa for 40 min. All the films exhibited a high transmittance over 80% in the visible and near-ultraviolet region. The band gap of as-grown films was about 3.50 eV.

Reduction of Chemical Reaction Mechanism for Halide-Assisted Silicon Carbide Epitaxial Film Deposition

Simulation of gas-phase and surface chemistry is an essential part in numerical study of chemical vapor deposition for film growth. When integrated with a model for transport processes such as gas flow, heat transfer, and mass transfer, it allows the prediction of gas-phase composition, film deposition rate, and film uniformity. For halide-assisted chemical vapor deposition of silicon carbide film growth, three-dimensional simulation of the deposition process can be time-consuming due to the large number of chemical reactions involved. In this study, a simplified chemical reaction mechanism was developed for silicon carbide growth with silicon tetrachloride and propane as precursors. After model validation, the reduced reaction steps were implemented into a three-dimensional simulation of halide-assisted chemical vapor deposition to predict the distributions of gas velocity, temperature, concentration of the intermediate reactants, and film deposition rate. Specifically, the effects of deposition pressure...

Effect of deposition pressure and post deposition annealing on SmCo thin film properties

AbstractIn this article we report on the effect of the deposition pressure and the post deposition annealing conditions on the structural and magnetic properties of SmCo thin films deposited on Si(100) wafers employing Ta buffer and capping layers. The films were deposited by DC magnetron sputtering and annealed in vacuum at various temperatures. The films under investigation were isotropic with high remanence magnetization, maximum coercive field of 8 kOe and a squareness ratio of coercivity higher than 0.9. It was found that the Ar pressure during the deposition is a key factor in controlling the stoichiometry and the structural and magnetic properties of the SmCo films, while the effect of the annealing temperature is crucial in optimizing the magnetic properties of the films. (© 2008 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Aggregation behavior and surface morphology studies of surfactin in Langmuir–Blodgett films

Surfactin monolayer, which was transferred from the air–water interface onto mica substrate by Langmuir–Blodgett (LB) technique, was characterized with atomic force microscopy (AFM). The effect of deposition pressure on morphologies of SuC14 (surfactin analogue with a β-hydroxyl fatty acid chain of 14 carbon atoms) LB films was investigated. AFM topographic image reveals phase separation at lower deposition pressure, indicating the existence of surfactin domains. At higher deposition pressure, the mica substrate was fully covered with surfactin monolayer, and spherical aggregates were formed atop the monolayer. Surfactin analogues (same polar head, different alkyl chain length) were applied to study the influence of the hydrophobic chain length on the aggregation behavior. On the basis of Fourier transform infrared (FTIR) measurements, the hydrogen bonding is supposed to be involved in the aggregates. These results, concerning the aggregates formation in surfactin LB films, provide new insights into the interfacial behavior of the amphiphilic lipopeptide at the air–water interface.

Effects of deposition pressure and plasma power on the growth and properties of boron-doped microcrystalline silicon films

Using diborane as doping gas, p-doped μc-Si:H layers are deposited by using the plasma enhanced chemical vapour deposition (PECVD) technology. The effects of deposition pressure and plasma power on the growth and the properties of μc-Si:H layers are investigated. The results show that the deposition rate, the electrical and the structural properties are all strongly dependent on deposition pressure and plasma power. Boron-doped μc-Si:H films with a dark conductivity as high as 1.42 Ω−1·cm−1 and a crystallinity of above 50% are obtained. With this p-layer, μc-Si:H solar cells are fabricated. In addition, the mechanism for the effects of deposition pressure and plasma power on the growth and the properties of boron-doped μc-Si:H layers is discussed.

Effect of deposition pressure on the properties of DLC coatings deposited by bipolar‐type PBII&amp;D

AbstractIn the present study, the effect of deposition pressure on the deposition rate and various properties of diamond‐like carbon (DLC) coatings were investigated. The DLC coatings were deposited on Si substrates using a bipolar‐type plasma‐based ion implantation and deposition plasma based ion implantation and deposition (PBIID) technique. The toluene was used as a source gas and the deposition pressure ranged from 0.03 to 2.0 Pa. The deposition rate of the DLC coatings increases about 12 times as the deposition pressure is changed from 0.03 to 2.0 Pa. Also, the surface roughness increases with increasing deposition pressure due to high deposition rate. The hardness and elastic modulus decrease when the deposition pressure exceed 0.7 Pa due to the remarkable growth of graphitic islands. The corrosion protection performance of the DLC coating deposited at 2.0 Pa is superior to that of the DLC coating deposited at 0.2 Pa for the same deposition time of 1 h. The high deposition pressure for the DLC coating is effective in improvement of corrosion protection properties. Copyright © 2008 John Wiley &amp; Sons, Ltd.