Deposition Of High-quality Films Research Articles

Recent Progress in Heat and Mass Transfer Modeling for Chemical Vapor Deposition Processes

Chemical vapor deposition (CVD) is a vital process for deposit of thin films of various materials with precise control over the thickness, composition, and properties. Understanding the mechanisms of heat and mass transfer during CVD is essential for optimizing process parameters and ensuring high-quality film deposition. This review provides an overview of recent advancements in heat and mass transfer modeling for chemical vapor deposition processes. It explores innovative modeling techniques, recent research findings, emerging applications, and challenges in the field. Additionally, it discusses future directions and potential areas for further advancement in CVD modeling.

ZIF-Based Metal-Organic Frameworks for Cantilever Gas Sensors

Among the different gas sensing platforms, cantilever-based sensors have attracted considerable interest in recent years thanks to their ultra-sensitivity and high-speed response. The gas sensing mechanism in a dynamic cantilever sensor is based on its resonance frequency shift upon adsorption of a gas molecule on the sensor. In order to sensitize the surface of a cantilever, a sensitive receptor material with large surface area is required. Metal-organic frameworks (MOFs) are a class of nanoporous crystalline materials composed of metal ions coordinated to organic linkers. MOFs are promising for gas sensing applications as they have large surface area, rich porosity with adjustable pore size and excellent selective adsorption capability for various gasses.[1] Zeolite imidazole frameworks (ZIFs) are a class of MOFs where metals with tetrahedral coordination (i.e. Zn, Co, Fe, Cu) are the central node and the ligands are imidazolate-based organic molecules.In this work, we developed a ZIF-based thin film for dynamic cantilever gas-sensing applications. We employed a novel atmospheric pressure spatial atomic layer deposition (AP-SALD)[2][3] technique to deposit a ZnO sacrificial layer on the silicon cantilevers. This technique allows the deposition of high-quality films at atmospheric pressure, faster than conventional ALD. The ZnO layer was then converted to a particular ZIF film with desired porosity and size, through a MOF-CVD process.[4] A gas-sensing bench setup was developed for the cantilever actuation and read-out. We present the chemical and morphological properties of the ZIF, as well as the frequency response of the sensor to various gases. The device showed reliable sensitivity to humidity, CO2 and several VOCs.

Optimization of selenization process to remove Ga-induced pin-holes in CIGS thin films

In thin-film solar cells, deposition of pinhole and the crack-free absorber layer, with the right chemical stoichiometry is highly important for high-performance solar cell devices. In solution-based CIGS solar cell technology, a nanoparticle ink approach provides phase stability of the final chalcogenide absorber layer. However, the sintering of small nanoparticles to form large grains with reduced grain boundaries is an important challenge in the fabrication process. This is usually realized by annealing in the Se atmosphere, i.e. selenization process. However, the presence of Ga in CIGS films leads to pinholes after selenization. In this study, the synthesis and deposition of high-quality films of CuInS2 (CIS) and CuIn0.75Ga0.25S2 (CIGS), are studied by using FESEM, XRD, EDS, and DLS characterization of CIGS and CIS nanoparticles and final films. We show that by selenization at reduced pressure and optimizing time and temperature, growing pinhole-free CIGS films with large grains is possible.

Engineering of CIGS nanoparticle inks for colloidal stability, uniform film formation and application as HTL for perovskite solar cells

In this work, synthesis of CuIn0.75Ga0.25S2 (CIGS) nanoparticles, the formation of stable dispersion, deposition of high-quality films and, fabrication of thin-film Perovskite solar cells are reported. The stability of nanoparticle ink is crucial in the formation of device-quality films. The chalcogenide-based materials are widely used in thin-film solar cells; in particular, Cu(In,Ga)S2 are used as an absorber and hole transporting layer. In the present study, the nanoparticles of about 20 nm size and bandgap of 1.5 eV are synthesized using a heat-up method. A variety of solvents are used as dispersing media and the stability of the inks is evaluated by precise optical monitoring. We observe a clear dependence of ink stability to the polarity index of the solvent, where the best stability occurs at a polarity index of about 0.26–0.36, corresponding to a range of solvents including chloroform. The thin films that are spin-coated using CIGS chloroform ink show large cracks, presumably due to the high vapor pressure of chloroform and evaporation-induced stress in the film. We resolve this problem through low-temperature deposition, which resulted in highly uniform pin-hole and crack-free films. Finally, the optimum deposition condition is used to fabricate perovskite solar cells having about 16.5% efficiency with CIGS as a hole transport layer.

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

Silicon nitride deposited by laser assisted plasma enhanced chemical vapor deposition for next generation organic electronic devices

Deposition of stoichiometric silicon nitride without damage and stress at low temperature using plasma enhanced chemical vapor deposition (PECVD) is an important issue in the application to various areas such as microelectronics, micro-electromechanical system (MEMS), etc. In this study, the effects of laser assistance during PECVD (LAPECVD) of silicon nitride on the physical and chemical characteristics of deposited Si3N4 film were investigated. The LAPECVD assisted by 193 nm laser at 80 °C showed higher deposition ratescompared to PECVD due to the enhanced dissociation of the reactant gases. In addition, the stoichiometric ratio of N/Si and the residual stress of the deposited silicon nitride film were improved. When the silicon nitride was directly deposited on the organic light emitting diode (OLED) for thin film passivation, no electrical damage was observed for LAPECVD possibly due to the coverage of a thin silicon nitride layer on the OLED surface by laser assisted deposition while conventional PECVD showed a damage of the device due to ion bombardment by direct exposure to plasma. We believe the LAPECVD system can be used for various next-generation microelectronic industries where high quality film deposition with minimized damage during PECVD at low temperature is required.

Effect of Annealing Temperature on Optical and Structural Properties of Solution Processed As2S3 Chalcogenide Glass Films

Abstract In the present paper, we report the effect of annealing temperature on optical properties of solution processed As2S3 Chalcogenide Glass (ChG) films. Solution processing of ChG films is a low cost, low temperature, scalable route for deposition of high quality films. Annealing of solution processed ChG films is a crucial step for the removal of residual solvent from the films. The optimization of the annealing temperature and corresponding optical properties of ChG films helps in better utilization of these films in functional devices. As2S3 glass was synthesized using melt quenching. The as-prepared As2S3 glass was dissolved in n-butylamine. The solution was then deposited onto glass substrates in the form of thin films. The as-prepared As2S3 glass films were annealed at different temperatures. As-annealed As2S3 glass films were studied using UV-Visible Spectroscopy, Infrared (IR) Spectroscopy, X-ray diffraction (XRD), Raman Spectroscopy and Energy Dispersive X-ray (EDAX) spectroscopy to undestand the effect of annealing on the structural and optical properties of the films

Solubilization of Carbon Nanotubes with Ethylene-Vinyl Acetate for Solution-Processed Conductive Films and Charge Extraction Layers in Perovskite Solar Cells.

Carbon nanotube (CNT) solubilization via non-covalent wrapping of conjugated semiconducting polymers is a common technique used to produce stable dispersions for depositing CNTs from solution. Here, we report the use of a non-conjugated insulating polymer, ethylene vinyl acetate (EVA), to disperse multi- and single-walled CNTs (MWCNT and SWCNT) in organic solvents. We demonstrate that despite the insulating nature of the EVA, we can produce semitransparent films with conductivities of up to 34 S/cm. We show, using photoluminescence spectroscopy, that the EVA strongly binds to individual CNTs, thus making them soluble, preventing aggregation, and facilitating the deposition of high-quality films. To prove the good electronic properties of this composite, we have fabricated perovskite solar cells using EVA/SWCNTs and EVA/MWCNTs as selective hole contact, obtaining power conversion efficiencies of up to 17.1%, demonstrating that the insulating polymer does not prevent the charge transfer from the active material to the CNTs.

Magnetic field influence on ionization zones in high-power impulse Magnetron Sputtering

High Power Pulsed Magnetron Sputtering (HPPMS) or High Power Impulse Magnetron Sputtering (HiPIMS) is a promising Ionized Physical Vapor Deposition (iPVD) technique that is capable of producing high quality, ultra-dense, wear-resistant, low-friction coatings with superior adhesion to the substrate. Despite the deposition of high quality films, HiPIMS suffer from lower deposition rates when compared to DC Magnetron Sputtering (dcMS). The cylindrically symmetric TriPack magnet pack which is the primary focus of this article has demonstrated increased deposition rates in HiPIMS compared to conventional magnet arrangement for the same average power. The observed difference in overall deposition rates, erosion area, voltage-current traces and pulsing parameters influence on deposition rates of TriPack from conventional magnet pack indicates that the plasma dynamics of TriPack is very different from the conventional magnet pack. In order to study the discharge dynamics of the cylindrically symmetric TriPack magnet pack, a gated ICCD camera was used to investigate the moving localized ionization zones in this magnet pack and conventional magnet pack for the same average power. Additionally, a simple HiPIMS ionization zone model was developed to predict the occurrence of ionization zones in TriPack and conventional magnetic field configurations under certain experimental/discharge conditions.

Self-Functionalization Behind a Solution-Processed NiOx Film Used As Hole Transporting Layer for Efficient Perovskite Solar Cells.

Fabrication of solution-processed perovskite solar cells (PSCs) requires the deposition of high quality films from precursor inks. Frequently, buffer layers of PSCs are formed from dispersions of metal oxide nanoparticles (NPs). Therefore, the development of trustable methods for the preparation of stable colloidal NPs dispersions is crucial. In this work, a novel approach to form very compact semiconducting buffer layers with suitable optoelectronic properties is presented through a self-functionalization process of the nanocrystalline particles by their own amorphous phase and without adding any other inorganic or organic functionalization component or surfactant. Such interconnecting amorphous phase composed by residual nitrate, hydroxide, and sodium ions, proved to be fundamental to reach stable colloidal dispersions and contribute to assemble the separate crystalline nickel oxide NPs in the final film, resulting in a very homogeneous and compact layer. A proposed mechanism behind the great stabilization of the nanoparticles is exposed. At the end, the self-functionalized nickel oxide layer exhibited high optoelectronic properties enabling perovskite p-i-n solar cells as efficient as 16.6% demonstrating the pertinence of the presented strategy to obtain high quality buffer layers processed in solution at room temperature.

Synthesis and properties of dicarbazolyltriphenylethylene-substituted fluorene derivatives exhibiting aggregation-induced emission enhancement

Abstract Two novel dicarbazolyltriphenylethylene-substituted fluorene derivatives DctF and Dct 2 F were synthesized by the Wittig-Horner and Suzuki coupling reactions. It was reasoned that introducing linear alkyl chains into the fluorene structure could facilitate the deposition of high-quality films by an economical and simple process. The thin solid films of DctF and Dct 2 F show strongly enhanced emissions in comparison to their dilute solutions, which indicate the aggregation-induced emission enhancement (AIEE). Their decomposition temperatures (T d) exceed 400°C and the glass transition temperature (T g) of DctF is 105°C. The maximum fluorescence emission wavelengths are in the region of 458–469 nm.

Modeling of gas flow and deposition profile in HWCVD processes

Hot wire chemical vapor deposition (HWCVD) is a powerful technology for deposition of high quality films on large area, where drawbacks of plasma based technology such as defect generation by ion bombardment and high equipment costs are omitted. While processes for diamond coatings using H2 and CH4 as precursor have been investigated in detail since 1990 and have been transferred to industry, research also focuses on silicon based coatings with H2, SiH4 and NH3 as process gases. HWCVD of silicon based coatings is a promising alternative for state-of-the-art radiofrequency-plasma enhanced chemical vapor deposition reactors. The film formation in HWCVD results from an interaction of several concurrent chemical reactions such as gas phase chemistry, film deposition, abstraction of surplus hydrogen bonds and etching by atomic hydrogen. Since there is no easy relation between process parameters and resulting deposition profiles, substantial experimental effort is required to optimize the process for a given film specification and the desired film uniformity. In order to obtain a deeper understanding of the underlying mechanisms and to enable an efficient way of process optimization, simulation methods come into play. While diamond deposition occurs at pressures in the range of several kPa HWCVD deposition of Si based coatings operates at pressures in the 0.1–30Pa range. In this pressure regime, particle based simulation methods focused on solving the Boltzmann equation are computationally feasible. In comparison to computational fluid dynamics this yields improved accuracy even near small gaps or orifices, where characteristic geometric dimensions approach the order of the mean free path of gas molecules. At Fraunhofer IST, a parallel implementation of the Direct Simulation Monte Carlo (DSMC) method extended by a reactive wall chemistry model is developed. To demonstrate the feasibility of three-dimensional simulation of HWCVD processes on realistic reactor geometries, we present DSMC simulations of static silicon deposition profiles on steel substrates in an in-line HWCVD coater in comparison with accordant experiments.

Highly photoluminescent low-temperature SiNx films in situ-deposited via SLAN ECR PECVD

Highly photoluminescent SiNx films were in situ-deposited at low temperatures using a slot-antenna electron-cyclotron-resonance (SLAN ECR) plasma. Spectroscopic ellipsometry, photoluminescence (PL) spectroscopy, high-resolution transmission electron microscopy (HRTEM), and UV–vis–NIR spectroscopy measurements were used to characterize the film. The SLAN ECR plasma, the ionization rate of which exceeds that of an RF plasma and a plasma density of approximately 1010–1011cm−3, is useful for high-quality film deposition at low temperatures. The deposited SiNx film displayed a high PL intensity, and as the SiH4/N2 ratio increased, the PL peak energy shifted from 2.8 to 1.7eV. These characteristics are useful for fabricating optoelectronic devices, such as LEDs and solar cells. As the silicon content in the SiNx film increased, the PL FWHM decreased. This effect deviated from the predictions based on the quantum confinement effect. The quantum dots did not properly form, as confirmed based on the HRTEM image. The linear relationship between the PL peak energy and the optical band gap energy suggested that bandtail recombination offered a more appropriate description of the PL mechanism than quantum confinement effects. Annealing and hyper-thermal neutral beam (HNB) treatment did not produce a shift in the PL peak, although the PL intensity decreased. These results also support the bandtail recombination model.

Electrochemical impedance spectroscopy and morphological analyses of pyrrole, phenylpyrrole and methoxyphenylpyrrole on carbon fiber microelectrodes

In this study, N-pyrrole (Py), N-phenylpyrrole (PhPy), and 1[4-methoxyphenyl]-1H-pyrrole (MPhPy) homopolymers were synthesized electrochemically onto carbon fiber microelectrodes (CFMEs). The influences of the substituent effect on electrochemical impedance spectroscopy (EIS) were studied comparatively. All the monomers were electrodeposited in 0.05 M tetraethyl ammonium perchlorate (TEAP)/dichloromethane (CH 2Cl 2) solution and characterized by cyclic voltammetry (CV), Fourier transform infrared reflectance spectrophotometry (FTIR-ATR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The morphological study reveals that the polymers were deposited as a continuous and well adhered film to surface of the CFME. An equivalent electrical circuit for three different monomers on CFMEs was proposed and experimental data were simulated to obtain the numerical values of circuit components. All results support the high quality film deposition that resulted in desired electronic properties due to the electron donating behaviors of substituent group of phenyl and methoxy.

Catalytically enhanced H 2-free CVD of transition metals using commercially available precursors

The deposition of metals using thermal CVD in a hydrogen-free atmosphere was investigated starting from nontoxic metalorganic precursors. A remarkably simple process, which relies on the chemical reduction by alcohols, allows the deposition of high-quality films of a variety of metals and alloys. The growth characteristics of metal films are investigated as a function of temperature, and their performance is discussed in terms of electrical resistivity. Near-bulk resistivities were obtained for Ni, Co, Cu, and Ag, while Fe presents a 37-fold higher resistivity than the bulk because of the poor packing of crystallites. In this work, the deposition conditions for the growth of single-phase cubic or hexagonal nickel were determined.

UHV arc for high quality film deposition

The vacuum arc is a well-known technique for producing coatings with enhanced adhesion and film density. Many cathodic arc deposition systems are actually in use in industry and research. They all work under (high) vacuum conditions in which water vapor pressure is an important source of film contamination, especially in the pulsed arc mode of operation. Here we present a cathodic arc system working under ultra-high vacuum conditions (UHVCA). We have used for arc ignition a Nd-YAG pulsed laser focused on the cathode surface, which provides a reliable system and allows eliminating all possible sources of contaminants. We have proven that the arc technique produces bulk-like films suitable for superconducting applications. UHVCA has been used to produce ultra-pure niobium films with excellent structural and electrical properties at a deposition temperature lower than 100 °C. The UHVCA technique therefore opens up new perspectives for all applications requiring pure films and low deposition temperatures.

Low-Temperature Deposition of TiN by Plasma-Assisted Atomic Layer Deposition

Titanium nitride () films were deposited by a plasma-assisted atomic layer deposition (PA-ALD) process, based on precursor dosing and remote plasma exposure, at temperatures ranging from 100 to . The plasma, the PA-ALD process, and the resulting material properties were extensively investigated. The plasma was studied by optical emission spectroscopy and Langmuir probe, revealing an ion density of and an electron temperature of just above the substrate. Under floating conditions there is thus a considerable ion flux towards the substrate per ALD cycle with a typical ion energy of . film growth was studied by in situ spectroscopic ellipsometry, revealing self-limiting surface reactions for the complete temperature range. At the growth rate of was found to be significantly lower than the growth rate of at . The stoichiometry of the films varied with the plasma exposure time, while the Cl content was mostly affected by the deposition temperature ( at to at ). Resistivities as low as were obtained at a temperature of , while at a fair resistivity of was reached. These results show that PA-ALD with and plasma is well suited for low-temperature deposition of high-quality films.

Optoelectronic properties of fluorine-doped silicon nitride thin films

Plasma-enhanced chemical vapor deposition (PECVD) of fluorine-doped silicon nitride (SiN x :F) has been investigated with a small amount of tetrafluorosilane (SiF 4) added into the SiH 4–NH 3 gas mixture. The influence of preparation conditions on the optical and electrical properties of the SiN x :F films has been systematically studied by XPS, FT-IR and UV–visible spectroscopy for optical property and current–voltage ramping measurement for electron conduction mechanism. It has been found that low radio frequency plasma power and the appropriate amount of SiF 4 addition favor the improvement of film properties to minimize the side effect for high quality film deposition such as etching effect from the dissociated SiF x and F radicals. Remarkably, deposition rate and optical band gap are higher than that in SiH 4–NH 3 gas chemistry even in the case of NH x radical deficient deposition conditions. SiN x :F films have lower hydrogen content and show rather rough and porous microstructure. However, the improvement of dielectric property can be obtained with high optical band gap (∼5.5 eV), resistivity (>10 17 Ω cm) and barrier height (>1.6 eV) for the trapped electron conduction even in the Si-rich nitride films.

Yttria-stabilized zirconia coatings produced using combustion chemical vapor deposition

A liquid fuel combustion chemical vapor deposition technique had been developed for oxide thin film deposition. Yttria-stabilized zirconia thin films had been processed using this technique operated in open air. Combustion flame had been modulated for high-quality film deposition by studying the effect of the ratio of the oxidant gas to the liquid fuel. Another key processing parameter, i.e. the substrate temperature, had been investigated. The as-grown films were characterized with X-ray diffraction and scanning electron microscope. The phase and crystallinity of the films were found strongly dependent on the experimental variables. Moderate increase of the ratio of the oxidant gas to the liquid fuel can accelerate the decomposition of the fuel and improve the quality of the deposited film. Two film growth kinetic modes were found with the transition temperature at approximately 1343 K. The microstructural zone transition temperature from zone 1 to zone 2 was found to be at approximately 1473 K. The processing variables were optimized with regard to both the phase quality and the growth rate.

Deposition of silicon alloys in an integrated distributed electron cyclotron resonance reactor: Oxide, nitride, oxinitrides, and multilayer structures

The films of SiOxNy were deposited in an integrated distributed electron cyclotron resonance reactor. Due to planar geometry, such deposition processes can be scaled-up for processing of large areas. Deposition kinetics and material properties were studied in order to find the common principles for obtaining faster growth rates and more uniform deposition of high quality films. Films were grown without bias at room temperature from mixtures of SiH4, O2, and N2 at high deposition rates (more than 4.5 nm/s for silica). Optical properties of the films were analyzed using ultraviolet (UV)-visible and infrared spectroscopic ellipsometry. The influence of gas flows, temperature, pressure, microwave power, and rf bias was investigated. A multilayer optical filter was grown on a polycarbonate substrate using a UV-visible ellipsometer to control the deposition process. The success of this test confirms the accuracy of the experimental results and shows high promise for the technology.