• Journal of the Korean Society for Heat Treatment
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• v.33 no.1
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• pp.20-24
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• 2020

Single crystal diamonds are in great demand in such fields as mechanical, electronic applications and optoelectronics. Large area single crystal diamonds are attracting attention in future industries for mass production and low cost. In this study, hot filament CVD (HFCVD) is used to grow large area single crystal diamond. However, the growth rate of large area single crystal diamond using HFCVD is known to be very low. The goal of this study is to use single crystal diamond substrates in HFCVD with methane-hydrogen gas mixtures to increase the growth rate of single crystal diamond and to optimize the conditions by analysing the effects of deposition conditions for high quality crystallinity. The deposition pressure, the ratio of CH₄/H₂ gas, the substrate temperature and the distance between the filament and the substrate were optimized. The sample used a 4×4 (mm²) size single crystal diamond substrate (100), the CH₄/H₂ gas ratio was fixed at 5%, the substrate temperature was synthesized to about 1000℃. At this time, the deposition pressure was changed to three types of 50, 75, 85 Torr and deposited. Finally, optimization was investigated under pressure conditions to analyse the growth rate and quality of single crystal diamond.

• Journal of the Korean Ceramic Society
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• v.26 no.3
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• pp.331-340
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• 1989

In this study, it was tried to deposit diamond films from a mixture of CH4 and H2 by the microwave plasma chemical vapor deposition(MWCVD). The MWCVD process was designed and set up from the 2.45GHz microwave generator. And the diamond film was successfully deposited on silicon wafers from the mixture of methane and hydrogen. The microstructures of the deposited diamond films were studied by using the following deposition variables : (a) methane concentration(0.6-10%), (b) reaction pressure(10-100torr), and (c) the substrate temperature(450-76$0^{\circ}C$).

• Journal of the Korean institute of surface engineering
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• v.44 no.4
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• pp.131-136
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• 2011

A kinetic study has been made for the growth of nanocrystalline diamond (NCD) particles to a continuous thin film on silicon substrate in a microwave plasma chemical vapor deposition reactor. Parameters of deposition have been microwave power of 1.2 kW, the chamber pressure of 110 Torr, and the Ar/$CH_4$ ratio of 200/2 sccm. The deposition has been carried out at temperatures in the range of $400\sim700^{\circ}C$ for the times of 0.5~16 h. It has been revealed that a continuous diamond film evolves from the growth and coalescence of diamond crystallites (or particles), which have been heterogeneously nucleated at the previously scratched sites. The diamond particles grow following an $h^2$ = k't relationship, where h is the height of particles, k' is the particle growth rate constant, and t is the deposition time. The k' values at the different deposition temperatures satisfy an Arrhenius equation with the apparent activation energy of 4.37 kcal/mol or 0.19 eV/ atom. The rate limiting step should be the diffusion of carbon species over the Si substrate surface. The growth of diamond film thickness (H) shows an H = kt relationship with deposition time, t. The film growth rate constant, k, values at the different deposition temperatures show another Arrhenius-type expression with the apparent activation energy of 3.89 kcal/mol or 0.17 eV/atom. In this case, the rate limiting step might be the incorporation reaction of carbon species from the plasma on the film surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.7
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• pp.552-556
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• 1998

Diamond thin films were deposited on Si substrate using $CH_4 and H_2$mixed gas by RF plasma CVD. Prior to deposition, the substrate surface was mechanically scratched with the diamond paste of $3{\mu}m$ to improve the density of nucleation sites. The microstructure of diamond films deposited with methane(0.5%~2%) at the reaction pressure ranging from 20 torr to 50torrr were studied by a scanning electron microscope. It was observed in the deposited diamond films that the nucleation density decreased and crystallinity increased with decreasing the methane concentration. However, the nucleation density and crystallinity were decreased with decreasing the process pressure.

• The Korean Journal of Ceramics
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• v.2 no.4
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• pp.177-180
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• 1996

Considerable progress in the development of CVD techniques for the deposition of diamond films has been achieved recently. Despite the polycrystalline structure of this material, its physical properties are now approaching those of natural type IIa diamond crystals. This paper will given some insight into the current status of CVD diamond thechnology with emphasis on optical and thermal applications. The role of process gas impurities like nitrogen will be discussed.

• Journal of the Korean institute of surface engineering
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• v.53 no.5
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• pp.241-248
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• 2020

The change of the deposition behavior of diamond through a pretreatment process of the base metal prior to diamond deposition using HFCVD was investigated. To improve the specific surface area of the base material, sanding was performed using sandblasting first, and chemical etching treatment was performed to further improve the uniform specific surface area. Chemical etching was performed by immersing the base material in HCl solutions with various etching time. Thereafter, seeding was performed by immersing the sanded and etched base material in a diamond seeding solution. Diamond deposition according to all pretreatment conditions was performed under the same conditions. Methane was used as the carbon source and hydrogen was used as the reaction gas. The most optimal conditions were found by analyzing the improvement of the specific surface area and uniformity, and the optimal diamond seeding solution concentration and immersion time were also obtained for the diamond particle seeding method. As a result, the sandblasted base material was immersed in 20% HCl for 60 minutes at 100 ℃ and chemically etched, and then immersed in a diamond seeding solution of 5 g/L and seeded using ultrasonic waves for 30 minutes. It was possible to obtain optimized economical diamond film growth rates.

• Journal of the Korean institute of surface engineering
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• v.28 no.3
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• pp.133-141
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• 1995

The deposition characteristics of diamond films were investigated for three different substrates : Si, Inconel 600 and steel. Diamond films were prepared by microwave plasma CVD method using $CH_4$, $H_2$ and $O_2$ as reaction gases. The deposited films were analyzed with SEM, Raman spectroscopy and ellipsometer. For Si substrate, diamond films were successfully obtained for most of the deposition conditions used in this study. As the $CH_4$ flow rate decreased and the $O_2$ flow rate increased, the quality of the film was improved due to the reduced non-diamond phase in the film. For Inconel 600 substrate, the surface pretreatment with diamond powders was required to deposit a continuous diamond film. The films deposited at temperatures of $600^{\circ}C$ and $700^{\circ}C$ had mainly diamond phase, but they were peeled off locally due to the difference in the thermal expansion coefficient between the substrate and the deposited films. The films deposited at $500^{\circ}C$ and $850^{\circ}C$ had only the graphitic carbon phase. For steel substrate, all of the films deposited had only the graphitie carbon phase. We speculated that the formation of diamond nuclei on the steel substrate was inhibited due to the diffusion of carbon atoms into the steel substrate which has a large amount of carbon solubility.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.229-233
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• 2011

Diamond thin films were deposited on pretreated Co cemented tungsten carbide (WC-6%Co) inserts as substrate by microwave plasma chemical vapor deposition (MPCVD) system, equipped with a 915MHz, 30kW generator for generating a large-size plasma. The substrates were pretreated with two solutions Murakami solution $[KOH:K_3Fe(CN)_6:H_2O]$ and nitric solution $[HNO_3:H_2O]$ to etch, WC and Co at cemented carbide substrates, respectively. The deposition experiments were performed at an input power of 10 kW and in a total pressure of 100 torr. The influence of various $CH_4$ contents on the crystallinity and morphology of the diamond films deposited in MPCVD was investigated using scanning electron microscopy (SEM) and Raman spectroscopy. The diamond film synthesized by the $CH_4$ plasma shows a triangle-faceted (111) diamond. As $CH_4$ contents was increased, the thickness of diamond films increased and the faceted planes disappeared. Finally, Faceted diamond changed into nano-crystalline diamond with random crystallinity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.240-248
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• 1998

The plasma chemical vapor deposition is one of the most utilized techniques for the diamond growth. As the applications of diamond thin films prepared by plasma chemical vapor deposition(CVD) techniques become more demanding, improved fine-tuning and control of the process are required. The important parameters in diamond film deposition include the substrate temperature, $CH_4/H_2$ gas flow ratio, total, gas pressure, and gas excitation power. With the spectroscopic ellipsometry, the substrate temperature as well as the various parameters of the film can be determined without the physical contact and the destructiveness under the extreme environment associated with the diamond film deposition. It is introduced how the real-time spectroscopic ellipsometry is used and the data are analyzed with the view of getting the growth condition and the accompanied features for a good quality of diamond films. And it is determined the important parameters during the diamond film growth, which include the final sample will be measured with Raman spectroscopy to confirm the diamond component included in the film.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.240-241
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• 2006

Metal/diamond binary composite coatings on Al substrate without grit blasting were deposited by cold spray process with insitu powder preheating. Microstructural characterization of the as-sprayed coatings with different diamond size, strength and with/without Ti coating on diamond was carried out by OM and SEM. The assessment of basic properties such as tensile bond strength and hardness of the coatings, and the deposition efficiency was also carried out. Particular attention on the composite coatings was on the diamond fracture phenomenon during the cold spray deposition and the interface bonding between the diamond and the Fe-based metal matrix.