Effect Of Various Deposition Parameters Research Articles

Effect of RF sputter power on deposition of CZTX (X[dbnd]S, Se) active layer without selenization/sulfurization, for solar cell applications

Copper Zinc Tin Selenide Cu2ZnSnSe4 (CZTSe) and Copper Zinc Tin Sulfide Cu2ZnSnS4 (CZTS) thin films were deposited from a multicomponent single target with different RF sputter powers and a constant annealing temperature of 450°C. One step deposition with in-situ annealing was performed in order to avoid the individual metal losses during the process. Effects of various deposition parameters were investigated to finely control the elemental ratio of the quaternary target which in-turn helps to obtain the desired stoichiometry suitable for solar absorber materials as confirmed from EDS analysis. The phase purity of thin films was investigated and confirmed using XRD and Raman spectroscopy. A thin film solar cell device with n-CdS, ZnO, ZnO:Al layers and Al grids over the prepared kesterite CZTX (X = S, Se) films were deposited on Mo coated soda lime glass using complete vacuum deposition technique. Even though the optical, electrical and structural results are promising, the conversion efficiency for these single step processed CZTSe and CZTS solar cell devices were limited to 3.72% and 2.6% due to possible interface effect and smaller grain size of the deposited films. Considering the industrial fabrication of kesterite thin film solar cells, this processes assures an environmental friendly approach with inherent purity leading to one-step reduction in the mass production process.

Effect of Growth Parameters on MoS2 Film Quality Deposited by Low-Temperature MOCVD Using I-Pr2DADmo(CO)3 and (t-C4H9)2S2

ABSTRACT Molybdenum disulfide (MoS2) is one of the representative two-dimensional layered material that is being actively researched for application in various fields owing to its characteristics such as a moderately wide bandgap (~1.8 eV) and excellent stability. Particularly promising applications include thin film transistors (TFTs) for displays and three-dimensional integrated circuits (3D-ICs). However, applications in these fields require direct deposition of high-quality films at a low temperature in order to meet the conditions such as the softening temperature of the glass for displays (<500-600°C) and the process temperature in the back-end of line of semiconductor device fabrication (<500°C). Low-temperature fabrication of MoS2 thin film using metalorganic chemical vapor deposition (MOCVD) has already been demonstrated in several previous studies [1-3]. However, they include processes such as long deposition times of about 10 hours or more [1,3], the use of highly toxic hydrogen sulfide (H2S) [2,3], and the addition of NaCl as a growth promoter [1,3]. These processes may lead to decrease in productivity and safety problems which would result in cost increase, and decrease in device reliability due to sodium contamination. These problems are considered to be bottlenecks for industrial and practical use. Our previous report examined process strategies that could overcome these challenges [4]. As a molybdenum precursor, we adopted i-Pr2DADMo(CO)3, which shows high adsorption and is expected to improve the throughput and suppress parasitic gas phase reactions. As a sulfur precursor, we used (t-C4H9)2S2, which is non-toxic as opposed to H2S. For the samples in our study, we demonstrated low-temperature (≤500°C) growth of MoS2 thin film without adding NaCl. However, the grain size was very small, about 10 nm, suggesting that it is necessary to improve the film quality for device application. Therefore, the purpose of this study is to investigate the effects of various deposition parameters on film growth and to provide guidelines for process optimization for improvement of film quality.In this study, the growth of MoS2 thin films by MOCVD was carried out in a cold wall type reactor, and the above-mentioned organic compounds were used as Mo and S precursors, and sapphire (0001) was used as the substrate. The samples were evaluated for film morphology by scanning electron microscope (SEM), Atomic Forth Microscopy (AFM) and film composition by X-ray photoelectron spectroscopy (XPS).Figure 1 (a) shows the surface SEM images of each sample with the S precursor supply rate set from 0.2 to 1.5 sccm while keeping the Mo precursor supply rate constant at 4.9 x 10-3 sccm. In addition, Fig. 1 (b) shows the average grain size and nucleation density calculated from 6 points in the sample with respect to the S precursor supply rate. As the S precursor supply rate increased from 0.2 to 0.7 sccm, decrease in nucleation density and increase in grain size up to approximately 110 nm were confirmed. It has been reported that the critical radius of clusters is larger for the clusters with stoichiometric composition than those with higher metal ratio with lacking chalcogen [5]. Therefore, it is considered that nucleation was suppressed by the increase in the critical radius of the cluster induced by the increase in the supply rate of S precursor. On the other hand, when the S precursor supply rate was further increased to 1.5 sccm, the nucleation density increased and the grain size decreased. This suggests that the S precursor supply rate have an optimum value within the range investigated in this study. We also evaluated the effect of temperature, pressure, and so on.This work was partly supported by JST CREST Number JPMJCR16F4, Japan. This work was also partly supported by JSPS KAKENHI Grant Number 18J22879. REFERENCE Kang, S. Xie, L. Huang, Y. Han, P. Y. Huang, K. F. Mak, C.-J. Kim, D. Muller, and J. Park, Nature 520, 656 (2015). Mun, Y. Kim, I.-S. Kang, S. K. Lim, S. J. Lee, J. W. Kim, H. M. Park, T. Kim, and S.-W. Kang, Scientific Reports 6, 21854 (2016). Mun, H. Park, J. Park, D.H. Joung, S.-K. Lee, J. Leem, J.-M. Myoung, J. Park, S.-H. Jeong, W. Chegal, S.W. Nam, and S.-W. Kang, ACS Appl. Electron. Mater. 1 (4), 608 (2019). Yamazaki, Y. Hibino, Y. Oyanagi, Y. Hashimoto, N. Sawamoto, H. Machida, M. Ishikawa, H. Sudo, H. Wakabayashi and A. Ogura, MRS Advances 5, 1643 (2020). Yue, Y. Nie, L. A Walsh, R. Addou, C. Liang, N. Lu, A. T Barton, H. Zhu, Z. Che, D. Barrera, 2D Mater. 4, 045019 (2017). Figure 1

Effect of Growth Parameters on MoS2 Film Quality Deposited by Low-Temperature MOCVD Using I-Pr2DADmo(CO)3 and (t-C4H9)2S2

This study investigates the effect of various deposition parameters on the MOCVD film growth and provide guidelines for process optimization for the film quality improvement. As a typical result, 93 % coverage with average grain size of 70-80 nm and maximum grain size of approximately 110 nm was achieved in 4 h deposition time at 450°C using non-toxic precursors. Further improvement can be expected by CVD apparatus refinement for uniform precursor supply and/or sample rotation.

Effect of substrate temperature, laser energy and post-deposition annealing on the structural, morphological and optical properties of laser-ablated perovskite BaSnO3 films

Perovskite BaSnO3 thin films suitable for excitonic solar cell applications were deposited on quartz substrate by pulsed-laser ablation method. The effect of various deposition parameters on the structural, morphological and optical properties is systematically studied by various characterization techniques. Phase-pure films with cubic crystalline nature were evolved at a substrate temperature of 600 °C with a laser energy of 60 mJ and post-deposition annealing further improved the structural purity and optical quality of the films. An exponential growth in film thickness was observed with increasing laser energy in which Stranski–Krastnov growth mechanism dominated. Chemical states of BaSnO3 were confirmed from XPS analysis. The deposited films present luminescence in the visible region at 452 nm, 480 nm and 580 nm wavelength.

Microstructure and mechanical performance of (AlCrNbSiTiV)N films coated by reactive magnetron sputtering

(AlCrNbSiTiV)N films are prepared on cermet cutter tool substrates using direct current reactive magnetron sputtering with a high-entropy alloy target. The use of a grey based Taguchi method to determine the deposition parameters of (AlCrNbSiTiV)N films has been studied by considering multiple performance characteristics. Taguchi quality design concept with an \(\hbox {L}_{9}\) (\(3^{4}\)) orthogonal array, signal-to-noise ratio and analysis of variance are used to determine the performance characteristics of the deposition process. The effect of various deposition parameters of (AlCrNbSiTiV)N films on the chemical composition, the microstructure, the morphology, the mechanical performance and cutting performance of the coated cutter in dry machining is determined. The experimental results show a cutter that is coated with (AlCrNbSiTiV)N exhibits less surface roughness (for workpiece) and flank wear (for cutter), so coated cutter tools have a much longer tool life than the uncoated tools. Transmission electron microscopy patterns confirm that the (AlCrNbSiTiV)N films have a polycrystalline face-centred cubic structure. In the confirmation runs, using grey relational analysis, there are improvements of 3.7% in surface roughness, 69.6% in flank wear and 3.2% in elastic recovery. The Rockwell adhesion test categorizes the coatings as class HF1.

Characterization of tin films synthesized from ethaline deep eutectic solvent

Abstract Tin (Sn) films were electrodeposited by galvanostatic method from ethaline deep eutectic solvent (DES), without any additives. The effect of various deposition parameters on the microstructure was studied. With increase in metal salt concentration from 0.01 to 0.1 M, changes in current–potential behaviour were observed in the polarization scans. This might be due to the existence of [SnCl 3 ] − , [Sn 2 Cl 5 ] − complexes in ethaline DES. Smooth and homogeneous deposits were obtained on a steel substrate surface by applying current density of 1.57 × 10 −3 A/cm 2 at 25 °C. Under these conditions the deposition rate was found to be 0.1 ± 10% μm/min and current efficiency was obtained as 84 ± 3%. XRD analysis of the deposit confirmed the polycrystalline tetragonal structure with mostly (2 0 0) orientation having a crystallite size about 62 ± 16% nm along with an internal strain of 0.0031 ± 22%. The present deposition method is simple, economical and can be adapted for industrial applications.

Textural and morphological studies on zinc–iron alloy electrodeposits

Zinc–iron alloy electrodeposits have industrial significance, since they provide better corrosion resistance and with improved mechanical properties when compared to pure zinc coatings. This is due to the unique phase structure of the alloy formed. But this deposition belongs to anomalous deposition, where the electrochemically less noble zinc deposits more preferentially, than the more noble iron. So the industrial process control over the deposition becomes difficult. So, this study correlates the effect of various deposition parameters over the deposition kinetics and deposited alloy characteristics. Transition and partial current densities were computed. Effect of hydrogen overpotential and surface coverage due to the adsorbed intermediates over anomalous deposition were explored. Plausible deposition mechanism and mathematical model was proposed to predict the anomalous electrodeposition characteristics. Textural, morphological and phase structural characteristics of the alloy was investigated. By the substitution of iron in the hcp lattice, c/a ratio was lowered and the lattice geometry was distorted. Intermetallic compounds of variable composition such as FeZn14, Fe5Zn33, Fe3Zn13 and FeZn3 with ‘η’ and ‘Γ’ phase structures were noted. Electrodeposition parameters were optimized and smooth, adherent, strain-free deposits with required iron content and hardness were obtained. The role of charge and mass transfer control on the texture and morphology of zinc–iron alloy electrodeposition was studied. Zinc-rich alloy with distorted ‘η’ hcp phase was predominant under kinetic limitations, by the iron substitution along ‘c’ axis. The ‘Γ’ phase with relatively iron-rich alloy was formed under diffusion control.

Hot-wire chemical vapor deposition and characterization of polycrystalline silicon thin films using a two-step growth method

A two-step growth method was proposed to reduce the amorphous incubation layer in the initial growth of polycrystalline silicon (poly-Si) films prepared by hot-wire chemical vapor deposition (HWCVD). In the two-step growth process, a thin seed layer was first grown on the glass substrate under high hydrogen dilution ratios ( φ ≥ 0.9), and then a thick overlayer was subsequently deposited upon the seed layer at a lower φ value. The effect of various deposition parameters on the structural properties of poly-Si films was investigated by Raman spectroscopy and transmission electron microscopy. Moreover, the electrical properties, such as dark and photo conductivities, of poly-Si films were also measured. It was found that the Si incubation layer could be suppressed greatly in the initial growth of poly-Si with the two-step growth method. In the subsequent poly-Si film thickening, a lower φ value of the reactant gases can be applied to enhance the deposition rate. Therefore, a high-quality poly-Si film can be fabricated via a two-step growth method with a sufficient growth rate using HWCVD.

Effect of various deposition parameters on the co-deposition behavior of cobalt antimony in citric-based solution

Direct current (dc) electrodeposition was used to co-deposit cobalt and antimony in citric-based solutions. Growth behavior of Co–Sb alloy thin films was systematically studied under various deposition conditions. Effects of deposition parameters (i.e., deposition potential, cobalt sulfate concentration, and pH value) on the microstructure, chemical, and phase composition of the deposited materials were also studied and are discussed in detail.

Effect of dynamic precursor gas pressure on growth behavior of amorphous Si–C–O nanorods by electron beam-induced deposition

Electron beam-induced deposition (EBID) is a versatile maskless technology [1] to fabricate submicronor nanometerscale structures from various elements in scanning electron microscope [2] as well as transmission electron microscope [3] and scanning transmission electron microscope [4]. During EBID, adsorbed precursor gas molecules on a substrate surface are irradiated and dissociated by an electron beam. This induces a chemical reaction that results in the deposition of non-volatile materials. If the electron beam is not moved relative to the substrate, a nanodot can be formed; electron beam scanning can produce nanorod within a suitable precursor gas pressure. Nanofabrication by using EBID is hence exceeding in terms of controlling the position and morphology of low dimensional functional nanostructures, e.g., carbon nanotube and ferromagnetic FePt alloy nanorods [5, 6]. It is very necessary to probe the effects of various deposition parameters on the target deposits, e.g., electron beam scan speed, precursor gas pressure, and deposition time, in order to fully develop and improve EBID serving as nanotechnology. No much importance, however, has been attached to dynamic precursor gas pressure in EBID, although it is generally known that the higher the precursor gas pressure is, the more the decomposed gas molecules are, and the larger the size of the deposits should be during EBID [7–9]. Undoubtedly, it will be the most direct route to know about the transport of precursor gas molecules by real-time monitoring (dynamic) precursor gas pressure, which helps to unravel the microscopic effect of gas pressure on the successive nanofabrication. In this paper, we will investigate the effects of dynamic precursor gas pressure and electron beam scan speed on the EBID process. Electron beam-induced deposition experiment was carried out in a 30 kV field emission gun scanning electron microscope (JEOL JSM-7800UHV). The electron beam current was about 0.8 nA with a beam diameter of 4 nm. The irradiation position and time of electron beam were controlled by an external voltage input to the beam deflectors using a computer with digital–analog converters. Tetraethoxy-silane SiOC2H5 was used as a precursor. A gas introduction system consists of a nozzle (its tip was about 1 mm away from the electron beam position, as shown in Fig. 1), gas pipeline, variable leak valve, and gas source reservoirs. The base gas pressure in the specimen chamber was 2 9 10 Pa and the maximum allowable gas pressure is 2 9 10 Pa. A holey carbon film was used as substrates. A 300 kV JEM-3000F field-emission gun transmission electron microscope, attached with a post-column Gatan imaging filter and a 1 k 9 1 k Ultrascan CCD camera, was employed to characterize the deposits by a high-resolution transmission electron microscopy (HRTEM) and energyfiltered transmission electron microscopy (EFTEM). To obtain elemental maps, the 3-window method [10] was applied, where the intensities from the first two windows (pre-edges 1 and 2) and third window (post-edge) are used for the background subtraction and the map, respectively. The sample was stabilized for 60 min before recording, in order to minimize the possible mechanical drift of the sample stage. When the focused electron beam position was moved into space at a certain speed (here 1.2–3 nm/s) along the edge of holey carbon film, freestanding rod-like nanostructures W. Zhang (&) K. Furuya National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003, Japan e-mail: phdweizhang@gmail.com

Incubation Effects upon Polycrystalline Silicon on Glass Deposited by Hot‐Wire CVD

AbstractA growth mechanism diagnosis for high‐rate, polycrystalline silicon deposition using hot‐wire CVD is explored in this article. The effects of various deposition parameters on the Si film growth are investigated by Raman spectroscopy and transmission electron microscopy (TEM) measurements, with special attention paid to the crystalline and amorphous phases. It is found that the H2/SiH4 ratio and substrate temperature (Ts) are the essential process parameters in determining the crystalline phase and the incubation thickness of the as‐deposited Si film. Under low hydrogen dilution conditions, an amorphous incubation layer was formed and degraded the crystalline fraction of the Si film. The incubation thickness prior to the nucleation decreases with the increase of the hydrogen dilution ratio. Under higher H2/SiH4 ratios (≥50), the amorphous phase deposited on the substrate could be etched selectively by the atomic hydrogen. As a consequence, nucleation of small crystallite occurs directly on the substrate. At low substrate temperatures, the deposition process shows the disadvantages of small grain size and low crystallinity. The poly‐Si film can be deposited from the seed layer under high Ts conditions (&gt;350 °C) where the Si appears singly crystallized at the initial stage and then grows epitaxially.

Diamond–DLC double layer used in corrosive protective coating

Pinhole-free diamond layers can widely be used in sensor technology as resistive coating against electrolyte solutions. The diamond layers created with chemical vapour deposition technique (CVD) are pinhole-free only above a certain thickness (at least 2.4 μm). Such layer thicknesses reduce the application possibilities. On the other hand, thin (∼200 nm) diamond like carbon (DLC) layers deposited by pulsed laser deposition technique (PLD) are pinhole free but have adhesion or contiguity problems depending on layer thickness. Utilizing the advantages of these two techniques a combined method was developed in order to prepare a pinhole free thin diamond–DLC double layer, for corrosion protection coating. The effects of various deposition parameters (such as background gas, temperature, bias, layer thickness) on the protective properties of the layers have been studied.

A study of AC reactive magnetron sputtering technique for the deposition of compositionally graded coating in the Cr–Al–N system

Cr 1− x Al x N coatings were deposited on various substrates using an inverted cylindrical AC magnetron sputtering system with chromium and aluminum targets, at a chamber pressure of 0.2 Pa (1.5 mTorr) for 1.5 h. The present study focuses on the effect of various deposition parameters, such as the N 2/Ar ratio and the target power on the properties of the coatings obtained. Some of the samples were subjected to oxidation in still air at 900 °C. The morphology and structure of these coatings were investigated by various analytical techniques such as XRD, SEM, EDAX and EDS. We report on the effect of processing parameters on the morphology, orientation, composition and oxidation behavior of the compositionally graded (Cr 1− x Al x )N coatings.

4H SiC Epitaxial Growth with Chlorine Addition

AbstractThe growth rate of a 4H‐SiC epitaxial layer has been increased by a factor of 19 (up to 112 μm h–1) with respect to the standard process, with the introduction of HCl in the deposition chamber. The epitaxial layers grown with the addition of HCl has been characterized by electrical, optical, and structural characterization methods. The effects of various deposition parameters on the epitaxial growth process have been described, and an explanation of this behavior in terms of the diffusion coefficient on the surface, Ds, and the ratio between the characteristic times, τD:τG, has been provided. The diodes, manufactured on the epitaxial layer grown with the addition of HCl at 1600 °C, have electrical characteristics comparable with the standard epitaxial process. This process is very promising for high‐power devices with a breakdown voltage of 10 kV.

Alumina thin films prepared by CO2laser deposition

CO2 laser deposition apparatus was newly developed, which enabled the high power laser- and the long time deposition without breaking window. Alumina thin films were deposited on stainless steel using a continuous CO2 laser (λ=10.6μm) for ablation of the alumina target.In this paper, the effect of various deposition parameters on hardness, deposition rate and adhesive strength of alumina films were investigated. Alumina films were analyzed using a scanning electron microscope (SEM), a X-ray diffractometer, an Auger electron spectroscope (AES) and a X-ray photoelectron spectron spectroscope (XPS). The results are summarized as follows.(1) Crack free films were formed at the substrate temperature of more than 673 K, although many cracks were observed in the films formed at room temperature.(2) Hard films more than Hk 1000 were formed under the pressure of less than about 1.33 Pa.(3) Depositon rate was controlled in the range of 10-3-8×10-2μm/s by varying the laser power, the ambient pressure and the distance between target and substrate. Deposition rate of this deposition method was much higher than that of Ion plating.(4) Film hardness had an excellent correlation with the deposition rate. Hard films more than Hk 2000 were formed with deposition rate of less than 3.3×10-3 μm/s.(5) Adhesive strength of hard films more than Hk 1000 by tensile test were higher than 40 MPa.(6) The deposition by a CO2 laser deposition resulted in stoichiometry close to the target.(7) Crystal structures of these films were found to be amorphous.

Optical and electrical properties of electron cyclotron resonance chemical vapour-deposited SiNx:H films

Silicon nitride (SiNx:H) films were deposited on both InP and Si substrates at temperatures ranging from room temperature to 400 °C by electron cyclotron resonance (ECR) plasma chemical-vapour deposition. The silicon source used was ditertiary butyl silane (SiH2(C4H9)2) that was activated by ECR plasmas composed of nitrogen alone or in combination with hydrogen or argon. The effects of various deposition parameters on the film properties are reported. The film indices of refraction ranged from 1.85 to 2.0, while the buffered HF etch rates were as low as 6 Å min−1 (1 Å = 10−10 m). Si/N ratios of the films ranged from 0.70 to 2.5, while the total hydrogen content was found to be approximately 20 to 25 at.%. Incorporation of carbon from the organic silicon source was efficiently suppressed (&lt; 1%) by the addition of a small amount of H2 to the ECR plasma gas. To study the electrical properties of the SiNx:H films, metal–insulator–semiconductor structures were fabricated. Film resistivities as high as 2 × 1015 Ω cm and insulator dielectric constants from 4 to 5 were measured.

ＣＯ２レーザ蒸着法によるアルミナ薄膜の作製

CO2 laser deposition apparatus was newly developed, which enabled the high power laser- and the long time deposition without breaking window. Alumina thin films were deposited on stainless steel using a continuous CO2 laser (λ=10.6μm) for ablation of the alumina target.In this paper, the effect of various deposition parameters on hardness, deposition rate and adhesive strength of alumina films were investigated. Alumina films were analyzed using a scanning electron microscope (SEM), a X-ray diffractometer, an Auger electron spectroscope (AES) and a X-ray photoelectron spectron spectroscope (XPS). The results are summarized as follows.(1) Crack free films were formed at the substrate temperature of more than 673 K, although many cracks were observed in the films formed at room temperature.(2) Hard films more than Hk 1000 were formed under the pressure of less than about 1.33 Pa.(3) Depositon rate was controlled in the range of 10-3-8×10-2μm/s by varying the laser power, the ambient pressure and the distance between target and substrate. Deposition rate of this deposition method was much higher than that of Ion plating.(4) Film hardness had an excellent correlation with the deposition rate. Hard films more than Hk 2000 were formed with deposition rate of less than 3.3×10-3 μm/s.(5) Adhesive strength of hard films more than Hk 1000 by tensile test were higher than 40 MPa.(6) The deposition by a CO2 laser deposition resulted in stoichiometry close to the target.(7) Crystal structures of these films were found to be amorphous.

NICKEL-COBALT SELECTIVE COATINGS BY CONVERSION PROCESS

ABSTRACT Black nickel-cobalt coatings have been found to be selective in the solar spectral region and to be more stable than the widely used conventional selective black nickel (NiS-ZnS) coatings. Solar selective black nickel-cobalt coatings formed on zincated aluminium, zinc electroplated aluminium and galvanised iron substrates by conversion process is described. Optical and thermal properties of the coatings are also reported. These coatings show an integrated solar absorptance ( α ) value in the range of 0.90 to 0.94 and a room temperature emittance (e ) in the range of 0.07 to 0.12. The effect of various deposition parameters and substrate preparation on the optical properties and microstructure has been reported. The plating parameters of various coatings have been determined, which yield the optimum optical and thermal properties of the final selective coatings. The thermal stability of the coatings as a function of annealing temperature and time, and the effect of thermal treatment on the optical...

Black nickel-cobalt: Selective coatings prepared by a conversion process

A solar selective black nickel-cobalt coating which is more stable than the widely used black nickel (NiS-ZnS) has been formed on zincated and zinc-electroplated aluminium substrates by a conversion process. Coatings with an integrated solar absorptance α in the range 0.90–0.94 and a room temperature emittance ε in the range 0.07–0.12 have been obtained. The effect of various deposition parameters on the optical properties and microstructure has been studied. The effect of thermal annealing in air at various temperatures on the optical properties and microstructure of the coatings has also been investigated.

Ion Beam Assisted Deposition of Metal Films

ABSTRACTThe chtaracteristics of ion beam assisted deposition are discussed and compared with those of photon beam assisted deposition. Effects of various deposition parameters including ion species, beam energy and substrate temperature are discussed. Deposited films usually include impurities such as C and O. Inclusion of oxygen takes place by enhanced oxidation by background oxygen and may be reduced by depositing in a clean vacuum. Promising applications of maskless ion beam assisted deposition are also discussed.