Plasma Chemical Vapor Deposition Method Research Articles

Influence of Co Removal for Improving Diamond Films Adhesive on WC-Co Substrates by DC-PCVD

The DC plasma chemical vapor deposition (DC-PCVD) method was a promising technique to fabricate CVD diamond coatings in industry, because it has many good properties, such as high grown rate of diamond films, big grown area, high qualities, and cost effective. In the present work, we synthesized diamond films on cemented carbide (YG6) substrates, and studied the different nitric acid aqueous solution treatment durations influence on diamond nucleation stage. The results indicated that well-chosen nitric acid aqueous solution treatment durations should be selected. For too short treatment times, the residual Co will promote the carbon transform from diamond metastable phase into graphite stable phase. On the other side, too long treatment times will consume too much Co, which will lead to the shortage of cohesive body, and finally the crackers in the bulk propagated and peeled off with the diamond films well grown on WC grains.

Freestanding diamond films phototransistor

High quality freestanding diamond (FSD) films with smooth nucleation surfaces were grown by microwave plasma chemical vapor deposition (MPCVD) method. A p-type hydrogenated surface conductivity of FSD film was obtained by using hydrogen plasma treatment. The annealing process in vacuum on the p-type behavior of FSD nucleation surfaces was investigated by Hall effect measurement. H-terminated diamond phototransistors were fabricated and the results suggest that they may be ideally suited for ultraviolet (UV) switching applications.

Deposition of TiC film on titanium for abrasion resistant implant material by ion-enhanced triode plasma CVD

Deposition of titanium carbide (TiC) layer on titanium (Ti) surface has been demonstrated by an ion-enhanced triode plasma chemical vapor deposition (CVD) method using a TiCl4+CH4+H2 gas mixture. Physical and mechanical properties of the deposited TiC film on Ti were investigated to examine its potential application as an abrasion resistant implant material. X-ray diffraction (XRD) showed that the specimen was consisted of TiC and Ti. Carbide layer of about 6μm thickness was observed on the cross section of the specimen by scanning electron microscopy (SEM). The Vickers hardness of surface carbide was more than 2000, which confirmed its high abrasion resistance.

Effect of diluent gas on silicon film deposition from a free jet of monosilane-diluent mixture activated by electron-beam plasma

Thin silicon films were synthesized by the gas-jet electron beam plasma chemical vapor deposition method from monosilane-argon, monosilane-argon-helium, and monosilane-argon-hydrogen mixtures. Addition of argon to the argon-silane mixture increased the deposition rate of silicon films, whereas addition of helium and hydrogen to the same mixture decreased the growth rate. It is shown that the process of silicon film deposition by this method from argon-monosilane mixture is primarily governed by fast secondary electrons, and argon dilution of mixture leads to increasing concentration of fast secondary electrons and increasing deposition rate of silicon films. Dilution of the initial mixture with helium or hydrogen causes a decrease in the deposition rate either due to gas-dynamic behavior of the supersonic jet of the mixture of light and heavy gases, or due to the etching effect of metastable helium atoms or hydrogen atoms on the surface of the growing silicon film.

Deposition of diamond-like carbon thin films containing photocatalytic titanium dioxide nanoparticles

Diamond-like carbon (DLC) thin films containing photocatalytic titanium dioxide (TiO2) nanoparticles were deposited by the plasma chemical vapor deposition method, which was developed by our group, using a colloidal solution as the precursor. It was found from the results of Raman spectroscopy, SEM observation and surface analyses that a bias voltage applied to the substrate had considerable effect on TiO2 nanoparticle inclusion in the matrix DLC thin film, and the optimal bias voltage was in the range from −50 to −175V. The depth profiling with Auger electron spectroscopy for the DLC thin film deposited at the bias voltage of −100V suggested that TiO2 nanoparticles were contained not only on the surface but also inside of the matrix thin film. To evaluate the photocatalytic properties of the deposited DLC thin films, methylene blue degradation, contact angle measurement, and antibacterial tests were performed. The results indicated that the DLC thin film containing TiO2 nanoparticles exhibited the abilities to decompose methylene blue dye, make the surface more hydrophilic and kill Escherichia coli cells under ultraviolet light irradiation.

Deposition of Cluster-Free B-doped Hydrogenated Amorphous Silicon Films Using SiH4+B10H14Multi-Hollow Discharge Plasma Chemical Vapor Deposition

We have deposited cluster-free B-doped hydrogenated amorphous silicon (a-Si:H) films using a SiH4+B10H14 multi-hollow discharge plasma chemical vapor deposition (CVD) method. We have studied the dependence of the deposition rate, band gap, and conductivity of the films on the gas flow rate ratio R=[B10H14]/[SiH4]. The deposition rate for SiH4+B10H14 plasmas is 2–3 times as high as that for pure SiH4 plasmas. Optical emission spectroscopy (OES) measurements indicate that SiH3 radical generation rate remains nearly constant regardless of R. These results suggest that BxHy radicals enhance the surface reaction probability and/or sticking probability of SiH3, being the predominant deposition precursor. Cluster-free B-doped a-Si:H films have a wide band-gap energy of 1.8–2.0 eV and a conductivity as high as 5.0×10-6 S/cm. These results demonstrate that cluster-free B-doped a-Si:H films deposited using SiH4+B10H14 multi-hollow discharge plasma CVD are promising as a p-layer of pin a-Si:H solar cells.

Deposition of Cluster-Free B-doped Hydrogenated Amorphous Silicon Films Using SiH4+B10H14 Multi-Hollow Discharge Plasma Chemical Vapor Deposition

We have deposited cluster-free B-doped hydrogenated amorphous silicon (a-Si:H) films using a SiH4+B10H14 multi-hollow discharge plasma chemical vapor deposition (CVD) method. We have studied the dependence of the deposition rate, band gap, and conductivity of the films on the gas flow rate ratio R=[B10H14]/[SiH4]. The deposition rate for SiH4+B10H14 plasmas is 2–3 times as high as that for pure SiH4 plasmas. Optical emission spectroscopy (OES) measurements indicate that SiH3 radical generation rate remains nearly constant regardless of R. These results suggest that BxHy radicals enhance the surface reaction probability and/or sticking probability of SiH3, being the predominant deposition precursor. Cluster-free B-doped a-Si:H films have a wide band-gap energy of 1.8–2.0 eV and a conductivity as high as 5.0×10-6 S/cm. These results demonstrate that cluster-free B-doped a-Si:H films deposited using SiH4+B10H14 multi-hollow discharge plasma CVD are promising as a p-layer of pin a-Si:H solar cells.

Combinatorial Deposition of Microcrystalline Silicon Films Using Multihollow Discharge Plasma Chemical Vapor Deposition

A high-pressure depletion method using plasma chemical vapor deposition (CVD) is often used to deposit hydrogenated microcrystalline silicon (µc-Si:H) films of a low defect density at a high deposition rate. To understand proper deposition conditions of µc-Si:H films for a high-pressure depletion method, Si films were deposited in a combinatorial way using a multihollow discharge plasma CVD method by which fluxes of H and SiH3 radicals and their flux ratio can be varied with the distance from the discharges. The higher gas pressure brings about the higher deposition rate, whereas the process window of device quality µc-Si:H films becomes quite narrower for the higher gas pressure.

Formation of Nanofibers on the Surface of Diamond-Like Carbon Films by RF Oxygen Plasma Etching

Diamond-like carbon (DLC) nanosize fibers were formed by etching DLC films using RF O2 plasma. The DLC films were grown on silicon substrates by an RF plasma chemical vapor deposition (CVD) method, and a small amount of Ni was deposited on the DLC films using a DC magnetron sputtering method before the etching. DLC fibers of 20 nm diameter and 600 nm height were found on the etched surfaces of the DLC films. DLC fibers of similar size that were highly insulating were also obtained by O2 etching without the deposition of Ni. It was found that Al from the RF electrode was sputtered and contaminated the DLC surface during etching, which would have affected the formation of fibers. The anisotropic etching of DLC and the ion-induced growth of carbon fibers are discussed as the formation mechanisms of the DLC fibers. The DLC fibers bent and stuck together during a field-emission scanning electron microscope observation, especially in the slow scanning mode. Such soft fibers can exist vertically and straightly throughout the etching in RF plasma.

A consideration of ternary C–H–O diagram for diamond deposition using microwave in-liquid and gas phase plasma

The purpose of this study is to clarify the mechanism of diamond synthesis using an in-liquid plasma chemical vapor deposition (CVD) method. We investigated the chemical reactions from a liquid mixture of methanol and ethanol (in-liquid plasma CVD) and a gas mixture of methane and hydrogen (gas-phase CVD). Carbon monoxide (CO) is firstly synthesized and then a chemical reaction using the remaining carbon (C) and hydrogen (H) is induced to synthesize a carbon substance. Residual H radicals act as an etchant removing the incompletely binding carbon atom that hinders diamond crystal growth. From spectroscopic measurements, CO peaks were clearly observed when the oxygen component is contained in the raw materials. From the experimental results of carbon deposits using various liquid and gas mixtures as the raw materials, we found that the region of the remaining H and C after CO synthesis satisfying H/C > 20 is necessary to synthesize diamonds using in-liquid plasma CVD method. The region of H/C > 20 in the Bachmann C–H–O diagram nearly agrees with the experimental results of synthesizing diamonds.

The Field Emission of Globe-Like Diamond Microcrystalline Aggregate Films

The globe-like diamond microcrystalline aggregates films were fabricated by microwave plasma chemical vapor deposition method. The field emission properties and emission stability of the films were tested using a diode structure in vacuum. It was found that the globe-like diamond microcrystalline aggregates films exhibited good electron emission properties and stability. The turn-on field of 0. 55 V /μm and the current density of 11mA/cm2 at the electric fields of 2.73V/μm were obtained. At the successive operator circles, the turn-on field tends to stabilize at 1. 08V /μm and the current density of 6.6 mA/cm2 is obtained.

Research on Output Power of Plasma for PCVD Synthesizing Silica Glass

Super purity silica glass was synthesized by Plasma Chemical Vapor Deposition (PCVD) method, during which inductively coupled plasma was used as the heat source. Influence of structure factor of tube and working gas on output power were discussed. The structure factor of tube was confirmed by analyzing the relation between structure factor of tube and coupling efficiency. With the increase of coupling efficiency, output power and plasma radius grow bigger. Super purity silica glass can be successfully synthesized when air was used working gas, during which input power was 100kW and output power reached to 40kW.

Growth and Field Emission Properties of the Carbon Complex Films

The carbon complex film, Which consists of diamond grains, carbon nanotubes, amorphous carbon composition, were fabricated by microwave plasma chemical vapor deposition （MPCVD） method. The ceramic with a Ti mental layer was used as substrate. The carbon complex films were evaluated by Raman scattering spectroscopy, x-ray diffraction spectrum, scanning electron microscope. The field emission properties were tested by using a diode structure in a vacuum. A phosphor-coated indium tin oxide anode was used for observing and characterizing the field emission. The turn-on field was only 0.55V/μm and emission current density as high as 11mA/cm2 was obtained under an applied field of 2.18V/μm for the first operation. The growth mechanism and field emission properties of the carbon complex films are discussed relating to microstructure and electrical conductivity.

Surface Modification of Si Wafer by Low-Pressure High-Frequency Plasma Chemical Vapor Deposition Method

In recent years, a flexible type of solar cell that can maintain various shape changes and that is applicable to virtually all products has attracted global attention. In the present research, we describe equipment for the production of thin-film material for flexible type solar cells that uses a high-frequency plasma chemical vapor deposition (CVD) method. This equipment is now at the development stage, and in order to clarify the cardinal trait of the plasma, we performed a plasma treatment on the surface of a Si wafer. Using X-ray photoelectron spectroscopy and contact angle meter measurements, we identified one index that clarifies the simple cardinal trait of plasma CVD.

Tribological Characteristics of CVD Nanocrystalline Diamond Film Grown by Bias Enhanced Nucleation Process

Nanocrystalline diamond (NCD) films on titanium alloys are of importance for tribology and biomedical implants. However, due to the different thermal expansion coefficients of the two materials, the complex nature of the interlayer formed during diamond deposition, and the difficulty in achieving high nucleation density, it is difficult to deposit adherent NCD films on titanium and its alloys. The aim of this research work is to successfully produce smooth, low roughness and well adherent NCD film on a pure Ti substrate by bias enhanced nucleation (BEN) process using microwave plasma chemical vapor deposition (MWPCVD) method. The friction coefficient was estimated to be around 0.06 in dry air using ball on disk tribometer with reciprocating sliding against a cemented carbide ball of 10 mm diameter at a high contact load of 20 N in dry air. The friction coefficient of bare Ti was between 0.55-06.

Nanocrystalline diamond growth in a surface-wave plasma

A surface-wave excited plasma is exploited in a diamond growth process by microwave plasma chemical vapor deposition method. Nanocrystalline diamond films with smooth surfaces are obtained from the plasma. As well as characterizing the deposited diamond films, the electron density and the electron temperature of the plasma are determined by using double-probe measurements. The plasma diagnosis reveals low electron temperatures of 2–3 eV in the process region, which is a distinctive characteristic of the surface-wave plasma. The low electron temperature is essential for the continuous re-nucleation of diamond in a hydrogen-rich plasma during the nanocrystalline diamond growth for a wide range of substrate temperature from under 100 to over 700 ∘C.

Pressure dependence of morphology and phase composition of SiC films deposited by microwave plasma chemical vapor deposition on cemented carbide substrates

SiC films were deposited on cemented carbide substrates by employing microwave plasma chemical vapor deposition method using tetramethylsilane (Si(CH 3) 4) diluted in H 2 as the precursor. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and scratching technique were used to characterize morphology, composition, phases present and adhesion of the films. Experimental results show that the deposition pressure has great influence on morphologies and phase composition of the films. In sequence, SiC films with a cauliflower-like microstructure, granular films with terrace-featured SiC particles coexisting with Co 2Si compound and clusters of nanometer SiC nanoplatelets appear as a function of the deposition pressure. In terms of plasma density and substrate temperature, this sequential appearance of microstructures of SiC films was explained. Adhesion tests showed that among the three types of films studied, the films with the terrace-featured SiC particles have relatively higher adhesion. Such knowledge will be of importance when the SiC films are used as interlayer between diamond films and cemented carbide substrates.

High mobility bottom gate nanocrystalline-Si thin-film transistors

We developed high mobility bottom gate nanocrystalline (nc)-Si thin-film transistors (TFTs). nc-Si film was deposited using inductively coupled plasma chemical vapor deposition method on SiNx gate insulator. Because of good film crystallinity and low ion damage, we could get high performance TFT characteristics. Our TFT showed field effect mobility of 9.4cm2 V−1 s−1 for electrons. These results showed that bottom gate nc-Si TFT could be used in applications such as next generation high definition television and organic light-emitting diode display.

沉积时间对球状微米金刚石聚晶结构的生长及其场发射特性影响

The globe-like diamond microcrystalline aggregates were grown in the different growing time by microwave plasma chemical vapor deposition method on the ceramic substrate with a Ti metal layer.The carbon films were evaluated by Raman scattering spectroscopy,X-ray diffraction spectrum,and scanning electron microscopy.The field emission properties were tested by using a diode structure in a vacuum.The growth mechanism of the carbon films and field emission properties of the globe-like diamond microcrystalline aggregates were discussed.It was found that different carbon films prepared by deposition time greatly changes in morphology,and field emission results also change a lot.The decrease of field enhancement factor and the growth of conductive channel are the main reasons for deterioration of the field emission effect.

Surface analysis of protein‐resistant, plasma‐polymerized ethylene glycol thin films

AbstractPoly(ethylene glycol) (PEG) has been widely used in biomedical applications because of its protein‐resistant and nontoxic properties. In this study, a plasma‐polymerized ethylene glycol (PPEG) thin film was deposited on a substrate using a capacitively coupled plasma chemical vapour deposition (CCP‐CVD) method with various plasma powers and ethylene glycol as a precursor. The surfaces of the PPEG thin films were characterized using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) along with a principal component analysis (PCA), and XPS. We confirmed that the PPEG thin film deposited at low plasma power closely resembles PEG polymers in terms of surface chemical composition and protein‐resistant property. To make patterned surfaces with protein‐resistant property for proteins, a PPEG thin film was first uniformly deposited on a glass slide and patterns were produced on the PPEG coated surface by depositing a plasma‐polymerized amine film through a metal shadow mask. When we spotted proteins on the patterned surface, they were immobilized only onto the plasma‐polymerized amine areas but not onto the PPEG areas. These results show that PPEG surfaces would be useful for the construction of various protein arrays. Copyright © 2010 John Wiley & Sons, Ltd.