Activated Reactive Evaporation Research Articles

Fabrication of perovskite solar cells with ITO deposited at a high rate by activated reactive evaporation using a pressure-gradient-type plasma gun

Indium tin oxide (ITO) as an electrode is generally sputtered to fabricate semitransparent perovskite solar cells (PSCs). In this work, ITO as the electrode of the PSC was deposited at a high rate (5 nm sec−1) by activated reactive evaporation (ARE) using a pressure-gradient-type plasma gun instead of sputtering. The power-conversion efficiency of the PSC with ITO (14.2%) deposited by ARE was comparable to that of a PSC with Ag (14.4%) deposited by thermal evaporation. This result shows that ARE is an effective method for depositing ITO to fabricate the semitransparent PSC.

Phase composition, microstructure, and tribological behavior of chrome-based ARE coatings

The paper deals with studying the structure, as well as the mechanical and tribological properties, of chrome-based coatings deposited by activated reactive evaporation (ARE) in the active atmosphere of N2, CO2, C2H2, and their binary mixtures (50: 50). Based on the data of the phase composition, conditions for the interaction of a metal being deposited with the active gas have been analyzed. A method of restoring the diffuse scattering by coatings deposited on substrates has been used to investigate specific features of the structural state formed in a coating synthesized in the acetylene-nitrogen mixture and containing the nanostructured carbide phase Cr3C2. The results have also indicated the possible formation of microdomains, which contain substantial amounts of free or hydrogenated solid carbon, in some of the coatings. This may explain the fairly high tribological characteristics of these coatings.

Electrochromic properties of nanocrystalline WO3 thin films grown on flexible substrates by plasma-assisted evaporation technique

Thin films of Tungsten trioxide (WO3) were deposited on ITO-coated flexible Kapton substrates by plasma-assisted activated reactive evaporation (ARE) technique. The influence of growth and microstructure on optoelectrochromic properties of WO3 thin films was studied. The nanocrystalline WO3 films grown at substrate temperature of 250°C were composed of vertically elongated cone-shaped grains of size 65 nm with relative density of 0.71. These WO3 films demonstrated higher optical transmittance of 85% in the visible region with estimated optical band gap of 3.39 eV and exhibited better optical modulation of 66% and coloration efficiency of 52.8 cm2/C at the wavelength of 550 nm.

Thickness dependence of the properties of indium tin oxide (ITO) FILMS prepared by activated reactive evaporation

Tin doped indium oxide thin films were prepared on glass substrates kept at room temperature, by activated reactive evaporation (ARE). Structural, electrical and optical properties were studied for films having different thickness. The resulting films are polycrystalline and show ˜ 90 % transmission in the visible region. Hall effect measurements at room temperature for a film with a nominal thickness of ˜ 350 nm shows a relatively high carrier concentration ˜ 6.3 × 10(20) cm-3, mobility ˜ 16 cm² V-1s-1, with a low resistivity ˜ 1.01×10-3W cm.

Synthesis of ZnO Nanoneedles on Flexible Polymer Substrates at Room Temperature by Activated Reactive Evaporation

Abstract: ZnO nanoneedles were successfully deposited on flexible polymer substrates at room temperature by activated reactive evapo-ration. Neither a catalyst nor a template was employed in this synthesis. These synthesized needles measured 500 - 600 nm in length and its diameter varied from 30 - 15 nm from the base to the tip. The single-crystalline nature of the nanoneedle was observed by high-resolution transmission electron microscopy studies. The Raman studies on these nanoneedles had shown that they are oxygen deficient in nature. A possible growth mechanism has been proposed here, in which the nanoneedles nucleate and grow in the gas phase by vapor-solid mechanism. Keywords: Nanoneedle, Activated reactive evaporation, ZnO, Gas phase, Nanostructures on flexible substrates. 1. INTRODUCTION Low dimensional nanostructured materials have attracted great interest because of their unique physical and chemical properties. ZnO, an important semiconductor of the II-VI group has many in-teresting properties such as wide band gap (3.37eV), large exciton binding energy, good piezoelectric characteristics, chemical stabil-ity and bio-compatibility [1, 2]. Nanostructures of ZnO have been widely investigated for potential application in UV laser, light emit-ting diode, sensors and solar cells [3-6]. Several techniques such as thermal evaporation, pulsed laser deposition (PLD), chemical vapor deposition (CVD) and molecular beam epitaxy (MBE) are widely employed to synthesis one dimensional (1D) ZnO nanostructures [7-11]. In general, all the above mentioned methods require high processing temperature and crystalline substrates for nanostructure growth. Hence they cannot be employed for synthesizing nanostruc-tures on flexible polymer substrates. Recently there has been increasing interest on the growth of 1D nanostructures over non-wafer based substrates such as flexible polymer and glass using inexpensive processing techniques. The assembly of semiconductor nanostructures on flexible polymer substrates is important and might provide merits in terms of per-formance, flexibility, shock resistance, reliability and cost over the analogous devices built on Si wafers. Combining the high flexibil-ity of the polymer substrates with the structural and electrical prop-erties of the semiconductor nanostructures may open up new areas of application such as flexible electronic devices and solar cells. Currently ZnO nanostructures on flexible polymer substrates for different applications are synthesized by wet-chemical techniques using different precursors and expensive top to bottom pattern transfer methods [4, 12-15]. To the best of our knowledge there is no report on the synthesis of 1D ZnO nanostructures on polymer substrates using an evaporation process. ZnO nanoneedles have been synthesized on highly flexible polymer and indium tin oxide (ITO) coated glass substrates at room temperature by activated reactive evaporation (ARE). The advan-tage of this process over the conventional process is that it does not require a catalyst or high substrate temperatures for the growth of the nanostructures [7, 8]. In this process nanostructures were syn-thesized at room temperature, independent of the substrate and relatively at high vacuum (~10

Characterization of ‘ARE’ deposited silicon nitride films and their feasibility as antireflection coating

Silicon nitride films are deposited in presence of nitrogen gas plasma by ‘Activated Reactive Evaporation (ARE)’ process on silicon substrates maintained at room temperature. Silicon powder was evaporated by e-beam evaporation in the presence of nitrogen gas plasma excited by a radio frequency (RF) power source (13.56 MHz). Depositions were carried out at different RF plasma powers. The deposited films were characterized by X-ray diffraction, X-ray photoelectron and UV–Visible spectroscopy, scanning electron microscopy and ellipsometry techniques. The X-ray diffraction pattern reveals the polycrystalline nature of the films with characteristics of hexagonal structure. X-ray photoelectron spectroscopy showed formation of silicon-rich silicon nitride. Observation of the films under scanning electron microscope shows a smooth and pinhole-free surface. The film deposited at 70 W RF plasma power for 18-min deposition time showed the refractive index (‘ η’ at λ = 632.8 nm) and the thickness ( d) 1.98 and 68.5 nm, respectively. The minimum reflectivity R = 1.74% is obtained from UV–Visible spectroscopy at λ = 547 nm. For the condition of near quarter wavelength single layer antireflection coating the optical thickness of the layer was taken as a quarter wavelength d = λ/4 η at the minimum reflectivity observed for the film. The above results show the feasibility of using ‘ARE’ silicon nitride as antireflection coating.

Deposition of indium nitride films by activated reactive evaporation process – a feasibility study

Indium nitride (InN) films are deposited by ‘activated reactive evaporation (ARE)’ process using parallel plate coupled nitrogen plasma (radio frequency source of 13.56 MHz) and evaporation of pure indium powder by resistive heating. Depositions are carried out by varying RF plasma power, on n-type silicon 〈1 0 0〉 substrate, maintained at room temperature, at a nitrogen gas pressure of 1.06 × 10 −1 Pa (8 × 10 −4 Torr). The film's crystallinity was examined by X-ray diffraction (XRD) and topography by scanning electron microscope (SEM). The diffraction pattern shows polycrystalline nature of the deposited films with characteristics of hexagonal structure. XRD peak intensity increases with increase in power. SEM observations show a smooth and pinhole free surface having improved quality of film with hexagonal structure as the power is increased from 60 to 120 W. Primary X-ray photoelectron spectroscopy (XPS) results show binding energies of the In 3d levels and N 1s level matching well with that of stoichiometric InN. Further, the refractive index of the films, measured by ellipsometry, is in the range of η = 2.79–2.91 with the variation of plasma power, which is in good agreement with the standard value for indium nitride ( η = 2.9). These results indicate the feasibility of using, ‘activated reactive evaporation (ARE)’ process for indium nitride depositions on silicon 〈1 0 0〉 substrates maintained at room temperature.

Characterization of indium nitride films deposited by activated reactive evaporation process

Indium nitride films are deposited in the presence of nitrogen plasma by ‘activated reactive evaporation (ARE)’ process on silicon substrate maintained at room temperature. Indium powder was evaporated by resistive heating in the presence of nitrogen plasma excited by a radio frequency (RF) power source (13.56 MHz). The refractive index of 2.91 obtained by ellipsometry, was in good agreement with that of the standard value of indium nitride ( η=2.9). Observation of the films by scanning electron microscope shows a smooth and pinhole-free surface and the diffraction pattern reveals the polycrystalline nature with characteristics of hexagonal structure. In3d 5/2, In3d 3/2 and N1s levels X-ray photoelectron spectra are observed at binding energies of 443.4 eV, 451.8 eV and 396.5 eV, respectively, indicating the formation of indium nitride. Fourier transform infrared spectrum of the deposited film shows the presence of InN bond. These results indicate the feasibility of the ARE process for the deposition of indium nitride on silicon 〈100〉 substrate maintained at room temperature.

Photochromic properties of double layer CdS/MoO 3 nano-structured films

The double layer CdS/MoO 3 devices were deposited on Pyrex glass substrates by sequential evaporation of CdS and nano-structured molybdenum trioxide (MoO 3) films using thermal and activated-reactive evaporation, respectively. The morphology and particle sizes of CdS and MoO 3 were determined by atomic force microscopy. The photochromic properties of the CdS/MoO 3 double layer were studied in the spectral range 300–1500 nm by illuminating them with the polychromatic light emitted by a tungsten lamp at various irradiation durations. The photochromic behaviour is observed to be more effective for generating colour centres in the In:CdS/MoO 3 double layer system.

Deposition of silicon films in presence of nitrogen plasma—A feasibility study

A design, development and validation work of plasma based ‘activated reactive evaporation (ARE) system’ is implemented for the deposition of the silicon films in presence of nitrogen plasma on substrate maintained at room temperature. This plasma based deposition system involves evaporation of pure silicon by e-beam gun in presence of nitrogen plasma, excited by inductively coupled RF source (13.56 MHz). The activated silicon reacts with the ionized nitrogen and the films get deposited on silicon substrate. Different physical and process related parameters are changed. The grown films are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and ellipsometry. The results indicate that the film contains silicon nitride and a phase of silicon oxy nitride deposited even at room temperature. This shows the feasibility of using the ARE technique for the deposition of silicon films in nitrogen plasma.

Synthesis of Copper Oxide Nanoparticles by Activated Reactive Evaporation Method

The present study reviews various synthesis techniques for preparing single-phase Cu2O nanoparticles. The ‘nanoparticle route’ results in the growth stable semiconductor materials via the size-induced stabilization at nanodimension. In comparison to other techniques, activated reactive evaporation (ARE) method has an excellent parametric control to obtain the nanoparticles in a wide size range. The size-dependent optical, structural and electronic properties of Cu2O nanoparticles prepared by ARE method have been discussed in detail. Increase in ionic nature of the Cu2O lattice and a surface-modified thin CuO shell surrounded Cu2O core stabilizes the Cu2O phase. High-energy heavy ion irradiation has been used to modify the nanocrystalline characteristics of the Cu2O nanophase without destroying nanoparticle nature. These results show that Cu2O nanoparticles based Schottky and heterojunction will be stable to yield better photovoltaic performance.

Characterization of silicon films deposited in presence of nitrogen plasma

Silicon films are deposited in presence of nitrogen plasma with the technique known as ‘activated reactive evaporation (ARE)’ with a view to deposit silicon nitride films on silicon substrate at room temperature. The in-house fabricated ARE system consists of a high vacuum chamber (e-beam gun housing) and a low vacuum chamber (reaction chamber) separated by a plate with an opening at the center. Silicon was evaporated by an electron beam (e-beam) gun in the presence of nitrogen plasma and films were deposited on a silicon substrate at room temperature. A number of experiments were carried out for testing the system and for checking the repeatability of the deposition of the films. The characterization of the films deposited on silicon substrates was done using X-Ray Diffraction, X-ray Photoelectron Spectroscopy and Energy Dispersive Analysis of X-ray (EDAX). Refractive index of 1.97 obtained from ellipsometric measurements is in good agreement with that of the standard value of silicon nitride. Observation under SEM showed particulates of silicon on the surface of the film. The same was confirmed from spot EDAX analysis. These results indicate that the deposited films are non-stoichiometric and contain both silicon nitride and a phase of silicon oxynitride.

Formation of Al-Cr-N Films by an Activated Reactive Evaporation (ARE) Method

The manufacturing conditions of Al-Cr-N films by ARE technique and their properties were studied in this investigation. Optical emission spectroscopy (OES) and mass spectrometry (MS) were powerful tools in monitoring the conditions of plasma to control the process. The Al/N ratios and the Cr/N ratios of Al-Cr-N films analyzed by EPMA showed good correlation to the A1/N ratios and the Cr/N ratios monitored by the OES method respectively. The crystal structure of the Al-Cr-N films changed from AIN phase to Cr 2 N phase with an increase in Cr content in the films. The resistivity to thermal oxidation of the Al-Cr-N films is superior to that of the usual Ti-Al-N films.

活性化反応性蒸着による透明バリアーアルミナ膜の生成と評価

Transparent Al2O3 films with high gas barrier properties were deposited on a PET film substrate by a web coating method using an activated reactive evaporation (ARE). The web speed was 100 to 700 m/min. The thickness of the Al2O3 film was 5 to 30 nm. ARE was beneficial for two reasons. One was the enabling of sound Al2O3 formation, and the other was the smooth winding of the Al2O3 deposited PET film achieved by neutralizing the negative charges, i.e., secondary electrons resulting from electron beam radiation on the Al evaporation source. The Al2O3 coated PET film showed an excellent barrier performance of about 1 g/m2 · day for water vapor transmission and about 1.5 cm3/m2 · day · atm for oxygen transmission, respectively, and an optical transmittance near to that of the uncoated PET. Results from analyses of Auger electron spectroscopy and X-ray diffraction, and observations of transmission electron microscopy and atomic force microscopy of the Al2O3 films are also described.

Epitaxial relationships and electrical properties of vanadium oxide films on r-cut sapphire

By activated reactive evaporation (ARE) at 500°C vanadium dioxide (VO 2) films could be grown epitaxially on r-cut sapphire. It is shown that there are two significantly different growth orientations of the VO 2 relative to the substrate. These orientations exhibit, however, a similar matching, which, in both cases, results in an additional small angle splitting. The corresponding domains can be described by the following epitaxial relation: (a) (100)VO 2//(011̄2)Al 2O 3 with [010]VO 2//[21̄1̄0] Al 2O 3 ±1.85° (b) (111)VO 2//(011̄2)Al 2O 3, with [101̄]VO 2//[21̄1̄0] Al 2O 3 +1.4° , and [1̄01]VO 2//[2̄110] Al 2O 3 +1.4° . These multidomain films show a well defined metal-to-insulator transition at 64°C with an accompanying resistivity change by four orders of magnitude. The related IR-reflectivity can be switched in this way by 67%.

活性化反応性蒸着法(ARE)によるTi-Al-N系皮膜の形成

活性化反応性蒸着法(ARE)によるTi-Al-N系皮膜の形成

Substrate bias effect of the activated reactive evaporation processed β-SiC thin films

β-SiC film prepared by the activated reactive evaporation (ARE) process, using Si as evaporation source and C 2H 2 as reactive gas, was proposed as a thermoelement of potential β-SiC/MoSi 2 thin film thermocouples [1]. In this paper, some of the important factors determining the sensor performance, i.e., structural, electrical, and mechanical properties of the silicon carbide films, were studied as a function of one of the important ARE process parameters, i.e., substrate bias, to improve the film quality and obtain the optimum deposition conditions for the β-SiC films with the properties suitable for thin film thermocouples. It was found that the film properties were very much dependent on substrate bias. The best quality β-SiC films with a C/Si ratio of 1.17 were obtained under optimum deposition conditions, i.e., C 2H 2 pressure 3 mTorr, substrate temperature 700 °C, ARE electrode voltage +150 V, and substrate bias −50V. Summarizing their electrical and mechanical properties: (i) conduction type, n-type; (ii) electrical resistivity, 4.8Ω·cm; (iii) carrier density, 6.5 × 10 16cm −3; (iv) Hall mobility, 19.4cm 2/Vs; (v) Vickers hardness, 3680 kg mm −2 at 25 g load; and (vi) Knoop hardness, 2060 kg mm −2 at 100 g load.

軟鋼のころがり疲労に及ぼすＴｉＮコーティングの影響

The surface of ring-like annealed mild steel specimens with diameter of 30mm and thickness of 8mm was coated with TiN film by an activated reactive evaporation (ARE) method. A pair of ring-like specimens contacted each other in the radius direction were set to the Nishihara type wear testing machine. They were rotated at the speed of 13.3rev./s under the condition of applied stress of 330 to 1100MPa and pure rolling contact with lubricant. The thin TiN film was uniformly produced on the surface of specimen by ARE method. This film adhered well to the surface of mild steel and it had enough bonding strength to mild steel even under pure rolling contact with lubricant. The annealed mild steel specimens coated with TiN had superior rolling contact fatigue strength than the uncoated ones. The fatigue life of the specimen coated with TiN was about eighteen times as large as that of the uncoated specimen under the same contact stress. TiN film on the surface of specimen was effective to suppress the generation of surface crack of specimens. The work hardening layer formed by repeated contact stress was near the surface of specimen and the degree of work hardening became larger with an increase in contact stress.

ＡＩＰ法によるＴｉ‐６０ａｔ％Ｈｆ合金の窒化物薄膜作製と反応性に関する研究

The arc ion plating (AIP) process uses a vacuum arc discharge with which almost all types of ceramic thin film can be formed. In this study, thin films of 40at% Ti-60at% Hf nitride were prepared on WC-Co substrates by AIP. The maximum microhardness obtained was Hv: 4000kgf/mm2. The crystal structure and orientation of the formed thin films were analyzed using X-ray diffraction (CuK α, 40kV-30mA). Reduced surface roughness and an increase deposition rate were studies as a function of nitrogen gas pressure.This process can be characterized by the high ionization rate of a metal vapor flux. Few studies have been made, however, on quantitatively assessing gas reactivity in a plasma process. The reaction probability of nitrogen gas in AIP was calculated from the viewpoint of metal-gas reaction kinetics, based on available data such as film deposition and nitrogen impingement rates on the substrate and compositional changes in films. The reaction probability (rN2=10-2) of nitrogen in Ti0.4Hf0.6N formation by AIP in this study was found to be equal to that in the hollow cathode discharge (HCD) process and higher than that in the activated reactive evaporation (ARE) by factors of three to ten.

Effects of activated reactive evaporation process parameters on the microhardness of polycrystalline silicon carbide thin films

Polycrystalline ß-SiC is expected to be an excellent material for thin film temperature sensors for the measurement of the surface temperature of gas turbine engine components operated at high temperatures (up to 1500°C). In this paper, Vickers and Knoop indentation microhardness tests were carried out on the silicon carbide films grown on Si(100) substrates by the activated reactive evaporation (ARE) process to measure one of the important mechanical properties, i.e. hardness of the films. The results of these tests are presented as a function of the ARE process parameters, such as C2H2 pressure PC2H2, substrate temperature Tsub, ARE electrode voltage VARE for the generation of d.c. glow discharge and substrate bias Vsub. It was found that the hardness of the films is very much dependent on these process parameters. A Vickers hardness value of 3680 kgf mm−2 (36.1 GPa) at 25 gf load (0.25 N) and a Knoop hardness value of 2060 kgf mm−2 (20.2 GPa) at 100 gf load (0.98 N) are obtained for polycrystalline ß-SiC films (C-to-Si ratio, 1.17) prepared under the following deposition conditions: C2H2 pressure, 3 mTorr (0.4 Pa); substrate temperature, 700°C; ARE electrode voltage, +150 V; substrate bias, −50 V.Microhardness variation of the ß-SiC films with applied load on the indenter was also studied. It was found that the hardness of the films decreases with increasing load, which is believed to be due to indentation size and substrate hardness effects.