Electron Cyclotron Resonance-metal Organic Chemical Vapor Deposition Research Articles

Preparation of Gold Nanoparticles Deposited Silicon Thin Film Electrode by Self-Assembly Method for the Employment of an Anode Material for Lithium Secondary Batteries.

This work describes a self-assembly method of gold nanoparticles coating on the surface of silicon thin films for the anode material of lithium secondary batteries. The preparation of the silicon thin films was carried out by electron cyclotron resonance metal organic chemical vapor deposition (ECR-MOCVD) process. The obtained films were further coated with (3-aminopropyl)-trimethoxysilane (APTMS) which has a role to bind the oxygen functional groups on Si surface and the gold nanoparticles. The dispersed gold nanoparticles on the surface of silicon thin films could be prepared due to self-assembly phenomena which interact between attraction and repulsion in gold nanoparticles colloidal solution (GNCS). The use of reducing agent of sodium citrate and tannic acid in GNCS significantly affected the size of gold nanoparticle in our experimental range. Based on our experimental results, the higher reversible capacity was exhibited for the silicon that was immersed in the GNCS consisted of only sodium citrate. The GNCS consisted of both sodium citrate and tannic acid produced severe coagulated nanoparticles when deposited on the silicon surface and thus inhibited the lithium movement from electrolyte to silicon surface. Consequently, the reversible capacity of silicon anode material with coagulated gold nanoparticles coating showed the reduced performance.

SnO2-coated LiCoO2 cathode material for high-voltage applications in lithium-ion batteries

Abstract In order to improve the electrochemical performances of LiCoO2 cathode in high voltage cycling range (3.0–4.5 V), SnO2 thin film has been deposited on the surface of electrode material by an electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD). Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns confirm the presence of SnO2 thin layers on the tape-casted electrode composed of nanocrystalline structure with agglomerated grain size ranging from 30 to 40 nm. The electrochemical tests show that the SnO2 coating layer significantly enhances the cycling performance of LiCoO2 cathode material. While the bare LiCoO2 cell does not work after 370 cycles, the surface-modified electrode exhibits the extended performance over 500 cycles with excellent capacity retention. In addition, it is also observed that SnO2 coating material is able to amplify the initial discharge capacity of bare LiCoO2 from 172 to183 mAhg− 1 at 1 C and effectively increase the coulombic efficiency of pristine LiCoO2 cathode. We conclude that these electrochemical improvements are strongly due to the suppression of charge transfer resistance and prevention of side reactions during the charge/discharge process via surface coating of electrodes.

Electrochemical behavior of a laser microstructured fluorine doped tin oxide anode layer with a plasma pretreatment for 3D battery systems

Fluorine-doped tin oxide (FTO) films with a thickness of about 3 micrometers were prepared by electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) under 800 W of microwave power, with tetra-methyl tin (TMT) as a tin precursor. The dome-shaped micro-patterned FTO layer was prepared on a copper current collector using a KrF excimer laser micromachining system for application as an anode for 3D lithium-ion batteries. Mild ECR plasma treatment at 600 W was carried out on the surface of the microstructured FTO anode, and the electrochemical characteristics were investigated with regard to the plasma treatment effects. The results show that physical properties such as the smooth and dense surface morphology and reduced surface oxygen functional groups of the plasma-treated samples enhanced the specific capacity, rate capability, and capacity fading. This was probably due to the reduction of side reactions, which may be closely related to the plasma treatment of the microstructured FTO layer. The ECR plasma treatment plays an important role in reducing the charging transfer resistance. In the experimental range studied, a higher specific capacity of 1425 mA h g−1 at a current density of 117 mA g−1 was observed, with capacity fading of 37.8% after 100 cycles for the plasma-treated microstructured FTO anode.

Characteristics of Fluorine-Doped Tin Oxide as a Transparent Heater on PET Prepared by ECR-MOCVD

The flexible transparent heater of fluorine-doped tin oxide (FTO) thin films on a polyethylene terephthalate (PET) was prepared by electron cyclotron resonance – metal organic chemical vapor deposition (ECR-MOCVD). Under plasma environment, the films were fabricated by supplying tetra-methyl tin (TMT) as precursors for tin, sulfur-hexafluorides (SF6) as precursor for fluorine atoms, oxygen and hydrogen for about 15 min deposition. The result shows that the FTO films have nanocrystalline structure with a grain size of 30-60 nm, a thickness of 300 nm and transmittance over 85 %. The observed lowest sheet resistance of 253 Ω/□ was found in our experimental range. We conclude the optimum fluorine doping plays an important role to affect the structural, electrical, optical and thermal properties of the FTO thin films as transparent materials.

Structural and Electrical Characteristics of Gallium Tin Oxide Thin Films Prepared by Electron Cyclotron Resonance-Metal Organic Chemical Vapor Deposition

Gallium tin oxide composite (GTO) thin films were prepared by electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD). The organometallics of tetramethlytin and trimethylgallium were used for precursors of gallium and tin, respectively. X-ray diffraction (XRD) characterization indicated that the gallium tin oxide composite thin films show the nanopolycrystalline of tetragonal rutile structure. Hall measurement indicated that the Ga/[O+Sn] mole ratio play an important role to determine the electrical properties of gallium tin composite oxide thin films. n-type conducting film obtained Ga/[O+Sn] mole ratio of 0.05 exhibited the lowest electrical resistivity of 1.21 x 10(-3) ohms cm. In our experimental range, the optimized carrier concentration of 3.71 x 10(18) cm(-3) was prepared at the Ga/[O+Sn] mole ratio of 0.35.

Effect of deposition temperature on the formation of the corrosion-protective SnOx:F coating layer on SUS 316 bipolar plates for PEMFC

Fluorine-doped tin oxide (SnOx:F) films on SUS 316 were prepared as a function of substrate temperature using electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) in order to achieve corrosion-resistant and low contact resistance bipolar plates for polymer electrolyte membrane fuel cells (PEMFCs). The SnOx:F films coated on SUS 316 substrate in the heating range from 200 to 500 °C were characterized by x-ray diffraction (XRD), Auger electron microscopy (AES) and field emission-scanning electron microscopy (FE-SEM). To simulate the aggressive PEMFC environment, all electrochemical experiments were conducted in 1 M H2SO4+2 ppm HF solution at 70 °C. With increases in the heat treatment temperature from 300 to 500 °C, it was shown that both corrosion resistance and interfacial contact resistance (ICR) substantially increase. The AES data revealed that the amount of fluorine decreases with increasing temperature in our experimental range. The deposition temperature appears to be one of the critical process parameters on the formation of the corrosion-protective layer for PEMFC bipolar plates. It is probably caused by microstructural evolution before/after potentiodynamic corrosion tests under the PEMFC environment.

Preparation of Fluorine Doped Zinc Tin Oxide Coating Layer on SUS 316 Bipolar Plates by ECR-MOCVD for PEMFC

Fluorine-doped zinc tin oxide (ZnSnOx:F) films on SUS316 are prepared by electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) in order to achieve the corrosion-resistant and low contact resistance bipolar plates for polymer electrolyte membrane (PEM) fuel cells. The prepared ZnSnOx:F films coated on SUS316 substrate are characterized by X-ray diffraction (XRD), auger electron microscopy (AES) and field emission-scanning electron microscopy (FE-SEM). To simulate the aggressive PEMFC environment, all of the electrochemical experiments are conducted in 1M H2SO4 + 2ppm HF solution at 70oC. The fluorine doping appears to be one of the critical process parameters on the formation of the corrosion-protective layer for PEMFC bipolar plates, as well as affecting the electrical properties of the films.

Effect of hydrogen content on the ZnO thin films on the surface of polyethylene terephthalate substrate through electron cyclotron resonance-metal organic chemical vapor deposition

Zinc oxide thin films were deposited on polyethylene terephthalate (PET) substrate by the electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) method at room temperature with the addition of hydrogen to the reaction gas. Diethyl zinc (DEZn) as the source precursor, O2 as oxidizer and argon as carrier gas were used for the preparation of ZnO film. Scanning electron micrography and X-ray diffraction analyses revealed that the ZnO grains with size of ca. 20 nm had an elliptic cylindrical configuration and were highly c-axis-oriented. The hydrogen content strongly affected the crystallographic structure, electrical property, and composition, as well as the surface roughness of the zinc oxide films. The chemical composition and surface states of the films were further examined by RBS and XPS to find the reason for the different electrical resistivity with variation of H2/Ar ratio. It can be concluded that hydrogen content plays an important role in increasing the Hall mobility, hole concentration, and electron concentration in our experimental range.

Characteristics of SnO<sub>x</sub>-ZnO Composite Film on Poly Ethylene Terephalate (PET) Substrate Prepared by ECR-MOCVD

Zinc oxide and tin oxide (ZnSnOx) films on PET (Polyethylene Terephthalate) substrate were prepared by the electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) under an hydrogen, oxygen and argon atmosphere. The used tin and zinc precursor are TMT (tetramethyltin) and DEZn(diethylzinc), respectively. The metal (Zinc and Tin) oxidation content plays an important role to control the optical and electrical characteristics of the films. Therefore the optimum DEZn/TMT content can be determined by the counter stability effect between oxidation and zinc-tin deposition. The obtained ZnSnOx (or SnOx-ZnO) of high mobility films exhibited c.a. 7.0×10-3 ohm ·cm of electrical resistivity.

Characteristics of Fluorine-Doped Tin Oxide Thin Films on Poly Ethylene Terephthalate (PET) Substrate

Fluorine-doped tin oxide (FTO) films on PET (Polyethylene Terephthalate) substrate were prepared by the electron cyclotron resonance-metal organic chemical vapor deposition (ECRMOCVD) under an Ar-O2-H2 atmosphere. The used tin and fluorine precursor are TMT (tetramethyltin) and sulfur hexafluoride (SF6), respectively. The hydrogen content plays an important role to control the optical and electrical characteristics of the films. The HF etching effect was clearly observed with increase of H2/TMT mole ratio, on the other hand the hydro-carbon deposition increased with decrease of H2/TMT mole ratio. Therefore the optimum H2 content can be determined by the counter balance effect between HF etching and hydro-carbon deposition. The obtained optimum SnO2: F thin films exhibited over 90 % of optical transmittance at wavelength range from 380 to 780 nm and c.a. 6×10-3 ohm ·cm of electrical resistivity at 1.25 H2/TMT mole ratio.

Characteristics of Cu/C films on polymer substrates prepared by ECR–MOCVD

Cu/C films were prepared at ambient temperature under a Cu(hfac)2-Ar-H2 atmosphere in order to obtain metallized polymer by using electron cyclotron resonance metal organic chemical vapor deposition(ECR-MOCVD) coupled with a direct current (DC) bias system. DC bias selectively attracts the positively charged copper ions and then makes them deposit on the polymer substrate. Structural analysis of the films by ECR showed that fine copper grains were embedded in an amorphous polymer matrix. The electrical properties of the films were closely related to the process parameters such as microwave power, magnet current, H2/Ar mole ratio and periodic negative voltage. The increase in H2 contents, microwave power, magnet current and the negative voltage brought on copper-rich film formation with low electrical resistance. On the other hand carbon-rich films with low sheet electrical resistance were prepared with lower values for process parameters described above. Formation of Cu/C films depends strongly on the periodic negative pattern of DC bias and the electrical sheet resistance of the films was controlled in the 108–100 ohm/sq range by process parameters of the ECR-MOCVD system.

The effect of direct current bias on the characteristics of Cu/C:H composite thin films on poly ethylene terephthalate film prepared by electron cyclotron resonance–metal organic chemical vapor deposition

Cu/C:H composite films were prepared on poly ethylene terephthalate (PET) substrate at room temperature by the electron cyclotron resonance–metal organic chemical vapor deposition (ECR-MOCVD) coupled with a negative direct current (DC) bias system. The negative DC bias voltage applied around the substrate strongly affected the crystallographic structure and composition as well as the surface roughness of the copper films. The surface resistivity of films decrease sharply as the bias voltage increase up to about 5 μΩ-cm below which the resistivity remains almost constant in the range of − 900 to − 1700 V. Thus, the bias voltage appeared to be a critical deposition parameter for preparing copper films with low resistivity. With interfacial studies of Cu-PET, copper atoms are embedded into the polymer substrate during the growth process. Therefore, Cu/C:H composite films on PET with good interfacial properties could be prepared by ECR-MOCVD coupled with a (−)DC bias system.

Effects of Pretreatments of PET Substrate on the Adhesion of Copper Films Prepared by a Room Temperature ECR-MOCVD Method

Effects of various pretreatments on the adhesion of copper-coated polymer films were investigated. Copper-coated polymer films were prepared by an electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) coupled with a DC bias system at room temperature. PET(polyethylene terephthalate) film was employed as a substrate material and it was pretreated by industrially feasible methods such as chromic acid, sand-blasting, oxygen plasma and ion-implantation treatment. Surface characterization of the copper-coated polymer film was carried out by AFM(Atomic Force Microscopy) and FESEM(Field Emission Scanning Electron Microscopy). Surface energy was calculated by based on the value of the contact angle measured. The adhesion of copper/PET films was determined by a pull-off test according to ASTM D-5179. It was found that suitable pretreatment of the PET substrate was required for obtaining good adhesion property between copper films and the substrate. In this study the highest adhesion was observed in sand-blasting, and then followed by those of acid and oxygen plasma treatment. However, the effect of surface energy was insignificant in our experimental range. This is probably due to compensating the difference in surface energy from various pretreatments by exposing substrate to ECR plasma for 5 min or longer at the early stage of the copper deposition. Therefore, it can be concluded that surface roughness of the polymer substrate plays an important role to determine the adhesion of copper-coated polymer for the deposition of copper by ECR-MOCVD.

Preparation and Characterization of Copper Film on Plastic Substrate by ECR-MOCVD Coupled with a DC Bias

AbstractCopper films were prepared at room temperature under a Cu(hfac)2-Ar-H2 atmosphere in order toobtain metallized plastics by using ECR-MOCVD (Electron Cyclotron Resonance Metal OrganicChemical Vapor Deposition) coupled with a DC bias system. Structural analysis of the films byECR showed that fine copper grains were embedded in an amorphous plastic matrix with goodadherence. Considering the AES result of the film prepared by ECR-CVD, we construe that thecopper film is chemically bonded with a plastic substrate. The delamination force determined bythe nano-scratch tester® showed in the range from 10 to 20mN.

Characteristics of Cu/C Films on Polymer Substrate Prepared by Room Temperature ECR-MOCVD Coupled with Periodic DC Bias

ABSTRACTCu/C films were prepared at room temperature under Cu(hfac)2-Ar-H2 atmosphere in order to obtain metallized polymer by using ECR-MOCVD (Electron Cyclotron Resonance Metal Organic Chemical Vapor Deposition) coupled with periodic DC bias system. Room temperature MOCVD was possible when periodic negative voltage was applied on the polymer substrate. The periodic negative voltage induces ions and radicals to have nucleation reaction on the surface of the substrate. Formation of Cu/C films strongly depends on the periodic negative pattern of DC bias and the electric sheet resistance of the films was controlled from 108 to 100ohm/sq ranges by process parameters such as microwave power and magnet current. The increase in microwave power and magnet current brought on copper-rich film formation with low electric resistance. On the other hand carbon-rich films with high sheet electric resistance were prepared with decreased values for process parameters aforementioned.

Effect of Plasma Parameter Control on the Growth of Zincblende Type GaN Films by ECR Plasma Enhanced Metalorganic Chemical Vapor Deposition

Zincblende type GaN films were grown at low temperatures by mesh-bias-controlled electron-cyclotron-resonance metalorganic chemical vapor deposition (ECRMOCVD) using ammonia and trimethylgallium as source gases. Dependence of plasma parameters such as electron temperature, electron density and plasma space potential in a discharge chamber and a growth chamber, on the mesh bias was investigated using a Langmuir probe and a Faraday cup. Dependence of the properties of GaN films, such as crystal structure, crystal orientation and residual stress, on the mesh bias applied during nitridation and growth was also investigated. The growth of zincblende GaN films was enhanced under conditions of a negative mesh bias at which the space potential was lowest and the impingement of ions was suppressed. The crystallinity of GaN films and their crystal orientation were best under the same bias conditions.