Selected-area deposition (SAD) of diamond films was achieved on silicon substrates with carbon film mask by hot filament chemical vapor deposition.Needle tip scraped lines were used to grow diamond films.Scanning elec...Selected-area deposition (SAD) of diamond films was achieved on silicon substrates with carbon film mask by hot filament chemical vapor deposition.Needle tip scraped lines were used to grow diamond films.Scanning electron microscope (SEM) investigation demonstrates that highly selective and sharp edged diamond films were produced.The results also demonstrate that the proper substrate temperature is very important for diamond selective growth in this deposition process.Since the enhancement of diamond growth was not observed on the needle tip scraped area of Si wafer with diamond powder scratching,the selective growth was considered to be closely correlated to silicon carbide formed during carbon film deposition and the residual carbon in the scraped area.展开更多
We report our observations on the higher carrier mobility and higher conductivity of sulfur-doped n-type diamond thin films synthesized by the hot filament chemical vapor deposi- tion （HFCVD）. The structural and ele...We report our observations on the higher carrier mobility and higher conductivity of sulfur-doped n-type diamond thin films synthesized by the hot filament chemical vapor deposi- tion （HFCVD）. The structural and electrical characterizations of the films are measured by X-ray diffraction （XRD）, Raman spectroscopy, scanning electron microscope （SEM）, energy dispersion X-ray spectra （EDX）, and Hall effect measurements. It is found that the sulfur atoms are in- corporated into the polycrystalline diamond films. The n-type conductivity of the films increases with the H2S concentration, and a conductivity of the films as high as 1.82 ^-l.cm-1 is achieved. The results show that the sulfur atom plays an important role in the structural and electrical properties of sulfur-doped diamond thin films.展开更多
A positive grid bias and a negative substrate bias voltages are applied to the self-made hot filament chemical vapor deposited （HFCVD） system. The high quality nanocrystalline diamond （NCD） film is successfully de...A positive grid bias and a negative substrate bias voltages are applied to the self-made hot filament chemical vapor deposited （HFCVD） system. The high quality nanocrystalline diamond （NCD） film is successfully deposited by double bias voltage nucleation and grid bias voltage growth. The Micro-Raman XRD SEM and AFM are used to investigate the diamond grain size, microstructure, surface morphology, and nucleation density. Results show that the obtained NCD has grain size of about 20 nm. The effect of grid bias voltage on the nucleation and the diamond growth is studied. Experimental results and theoretical analysis show that the positive grid bias increases the plasma density near the hot filaments, enhances the diamond nucleation, keeps the nanometer size of the diamond grains, and improves the quality of diamond film.展开更多
Diamond has extreme hardness and is a new type of multi-function material which has excellent electrical, optical, thermal and mechanical properties.Russian scientists Derjaguin et al. successfully synthesized diamond...Diamond has extreme hardness and is a new type of multi-function material which has excellent electrical, optical, thermal and mechanical properties.Russian scientists Derjaguin et al. successfully synthesized diamond on nondiamond substrates by chemical transport reaction method in 1976. In 1982, Japanese sci-展开更多
Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using acetone/ H<sub>2</sub>/Ar gas mixture by bias-enhanced hot filament chemical vapor deposition（HFCVD） technique.The evi...Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using acetone/ H<sub>2</sub>/Ar gas mixture by bias-enhanced hot filament chemical vapor deposition（HFCVD） technique.The evidence of nanocrystallinity,smoothness and purity was obtained by characterizing the sample with scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Raman spectroscopy,atomic force microscopy （AFM ）,and field emission transmission electron microscopy（FE-TEM ）.The results show that nanocrystalline diamond films consists of nanocrystalline diamond grains with sizes range from 20 to 80 nm and contain a large amount of grain boundaries.The surface roughness of the films is measured as R<sub>a</sub>【50nm.The Raman spectroscopy,XRD pattern,and FE-TEM image of the films indicate the presence of nanocrystalline diamond.A new process is used to deposit composite diamond coatings by a two-step chemical vapor deposition procedure,including first the deposition of the rough polycrystalline diamond and then the smooth fine-grained nanocrystalline diamond film.Such composite diamond coatings not only display good adhesion and wear resistant properties,but also have smooth surfaces that are liable to polishing.This coating technology can not only meet the requirement of the adhesion of diamond coatings,but also reduce surface roughness of diamond coatings effectively,thus remove the obstacles for the industrialization of CVD diamond coatings.The diamondcoated dies with these composite coatings show obvious effect in the practical application.展开更多
Hot-filament chemical vapor deposition ( HFCVD) is a promising method for commercial production of diamond films. Filament performance in heat transfer and hydrogen decomposition in reactive environment was investigat...Hot-filament chemical vapor deposition ( HFCVD) is a promising method for commercial production of diamond films. Filament performance in heat transfer and hydrogen decomposition in reactive environment was investigated. Power consumption by the filament in vacuum, helium and 2% CH4/H2 was experimentally determined in temperature range 1300℃-2200℃. Filament heat transfer mechanism in C-H reactive environment was calculated and analyzed. The result shows that due to surface carburization and slight carbon deposition, radiation in stead of hydrogen dissociation, becomes the largest contributor to power consumption. Filament-surface dissociation of H2 was observed at temperatures below 1873K, demonstrating the feasibility of diamond growth at low filament temperatures. The effective activation energies of hydrogen dissociation on several clean refractory flaments were derived from power consumption data in literatures. They are all lower than that of thermal dissociation of hydrogen revealing the nature of catalytic dissociation of hydrogen on filament surface. Observation of substrate temperature suggested a weaker role of atomic hydrogen recombination in heating substrates in C-H environment than in pure hydrogen.展开更多
Tribological properties of chemical vapor deposition (CVD) diamond films greatly affect its application in the mechanical field. In this paper, a novel multilayer structure is proposed, with which multilayer diamond f...Tribological properties of chemical vapor deposition (CVD) diamond films greatly affect its application in the mechanical field. In this paper, a novel multilayer structure is proposed, with which multilayer diamond films are deposited on silicon carbide by hot filament CVD (HFCVD) method. The different micrometric diamond grains are produced by adjusting deposition parameters. The as-deposited multilayer diamond films are characterized by scanning electron microscope (SEM) and white-light interferometry. The friction tests performed on a reciprocating ball-on-plate tribometer suggest that silicon carbide presents the friction coefficient of 0.400 for dry sliding against silicon nitride (Si3N4) ceramic counterface. With the water lubrication, the corresponding friction coefficients of silicon carbide and as-deposited multilayer diamond films further reduce to 0.193 and 0.051, respectively. The worn surfaces indicate that multilayer diamond films exhibit considerably high wear resistance.展开更多
By pre-treating substrate with different methods and patterning the catalyst, selective and patterned growth of diamond and graphitic nano-structured carbon films have been realized through DC Plasma-Enhanced Hot Fila...By pre-treating substrate with different methods and patterning the catalyst, selective and patterned growth of diamond and graphitic nano-structured carbon films have been realized through DC Plasma-Enhanced Hot Filament Chemical Vapor Deposition (PE-HFCVD). Through two-step processing in an HFCVD reactor, novel nano-structured composite diamond films containing a nanocrystalline diamond layer on the top of a nanocone diamond layer have been synthesized. Well-aligned carbon nanotubes, diamond and graphitic carbon nanocones with controllable alignment orientations have been synthesized by using PE-HFCVD. The orientation of the nanostructures can be controlled by adjusting the working pressure. In a Microwave Plasma Enhanced Chemical Vapor Deposition (MW-PECVD) reactor, high-quality diamond films have been synthesized at low temperatures (310℃-550℃) without adding oxygen or halogen gas in a newly developed processing technique. In this process, carbon source originates from graphite etching, instead of hydrocarbon. The lowest growth temperature for the growth of nanocrystalline diamond films with a reasonable growth rate without addition of oxygen or halogen is 260℃.展开更多
基金the Key Project of Chinese Academy of Sciences Knowledge Innovation Program (Grant No.KJCX3.SYW.N10)
文摘Selected-area deposition (SAD) of diamond films was achieved on silicon substrates with carbon film mask by hot filament chemical vapor deposition.Needle tip scraped lines were used to grow diamond films.Scanning electron microscope (SEM) investigation demonstrates that highly selective and sharp edged diamond films were produced.The results also demonstrate that the proper substrate temperature is very important for diamond selective growth in this deposition process.Since the enhancement of diamond growth was not observed on the needle tip scraped area of Si wafer with diamond powder scratching,the selective growth was considered to be closely correlated to silicon carbide formed during carbon film deposition and the residual carbon in the scraped area.
基金supported by the Fundamental Research Funds for Central Universities of China(No.10ML40)
文摘We report our observations on the higher carrier mobility and higher conductivity of sulfur-doped n-type diamond thin films synthesized by the hot filament chemical vapor deposi- tion （HFCVD）. The structural and electrical characterizations of the films are measured by X-ray diffraction （XRD）, Raman spectroscopy, scanning electron microscope （SEM）, energy dispersion X-ray spectra （EDX）, and Hall effect measurements. It is found that the sulfur atoms are in- corporated into the polycrystalline diamond films. The n-type conductivity of the films increases with the H2S concentration, and a conductivity of the films as high as 1.82 ^-l.cm-1 is achieved. The results show that the sulfur atom plays an important role in the structural and electrical properties of sulfur-doped diamond thin films.
文摘A positive grid bias and a negative substrate bias voltages are applied to the self-made hot filament chemical vapor deposited （HFCVD） system. The high quality nanocrystalline diamond （NCD） film is successfully deposited by double bias voltage nucleation and grid bias voltage growth. The Micro-Raman XRD SEM and AFM are used to investigate the diamond grain size, microstructure, surface morphology, and nucleation density. Results show that the obtained NCD has grain size of about 20 nm. The effect of grid bias voltage on the nucleation and the diamond growth is studied. Experimental results and theoretical analysis show that the positive grid bias increases the plasma density near the hot filaments, enhances the diamond nucleation, keeps the nanometer size of the diamond grains, and improves the quality of diamond film.
文摘Diamond has extreme hardness and is a new type of multi-function material which has excellent electrical, optical, thermal and mechanical properties.Russian scientists Derjaguin et al. successfully synthesized diamond on nondiamond substrates by chemical transport reaction method in 1976. In 1982, Japanese sci-
基金Supported by the National Natural Science Foundation of China(50575135)
文摘Nanocrystalline diamond films were deposited on Co-cemented carbide substrates using acetone/ H<sub>2</sub>/Ar gas mixture by bias-enhanced hot filament chemical vapor deposition（HFCVD） technique.The evidence of nanocrystallinity,smoothness and purity was obtained by characterizing the sample with scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Raman spectroscopy,atomic force microscopy （AFM ）,and field emission transmission electron microscopy（FE-TEM ）.The results show that nanocrystalline diamond films consists of nanocrystalline diamond grains with sizes range from 20 to 80 nm and contain a large amount of grain boundaries.The surface roughness of the films is measured as R<sub>a</sub>【50nm.The Raman spectroscopy,XRD pattern,and FE-TEM image of the films indicate the presence of nanocrystalline diamond.A new process is used to deposit composite diamond coatings by a two-step chemical vapor deposition procedure,including first the deposition of the rough polycrystalline diamond and then the smooth fine-grained nanocrystalline diamond film.Such composite diamond coatings not only display good adhesion and wear resistant properties,but also have smooth surfaces that are liable to polishing.This coating technology can not only meet the requirement of the adhesion of diamond coatings,but also reduce surface roughness of diamond coatings effectively,thus remove the obstacles for the industrialization of CVD diamond coatings.The diamondcoated dies with these composite coatings show obvious effect in the practical application.
基金Supported by the National Natural Science Foundation of China under contract No.59976038.
文摘Hot-filament chemical vapor deposition ( HFCVD) is a promising method for commercial production of diamond films. Filament performance in heat transfer and hydrogen decomposition in reactive environment was investigated. Power consumption by the filament in vacuum, helium and 2% CH4/H2 was experimentally determined in temperature range 1300℃-2200℃. Filament heat transfer mechanism in C-H reactive environment was calculated and analyzed. The result shows that due to surface carburization and slight carbon deposition, radiation in stead of hydrogen dissociation, becomes the largest contributor to power consumption. Filament-surface dissociation of H2 was observed at temperatures below 1873K, demonstrating the feasibility of diamond growth at low filament temperatures. The effective activation energies of hydrogen dissociation on several clean refractory flaments were derived from power consumption data in literatures. They are all lower than that of thermal dissociation of hydrogen revealing the nature of catalytic dissociation of hydrogen on filament surface. Observation of substrate temperature suggested a weaker role of atomic hydrogen recombination in heating substrates in C-H environment than in pure hydrogen.
基金the National Natural Science Foundation of China (No. 50975177)
文摘Tribological properties of chemical vapor deposition (CVD) diamond films greatly affect its application in the mechanical field. In this paper, a novel multilayer structure is proposed, with which multilayer diamond films are deposited on silicon carbide by hot filament CVD (HFCVD) method. The different micrometric diamond grains are produced by adjusting deposition parameters. The as-deposited multilayer diamond films are characterized by scanning electron microscope (SEM) and white-light interferometry. The friction tests performed on a reciprocating ball-on-plate tribometer suggest that silicon carbide presents the friction coefficient of 0.400 for dry sliding against silicon nitride (Si3N4) ceramic counterface. With the water lubrication, the corresponding friction coefficients of silicon carbide and as-deposited multilayer diamond films further reduce to 0.193 and 0.051, respectively. The worn surfaces indicate that multilayer diamond films exhibit considerably high wear resistance.
文摘By pre-treating substrate with different methods and patterning the catalyst, selective and patterned growth of diamond and graphitic nano-structured carbon films have been realized through DC Plasma-Enhanced Hot Filament Chemical Vapor Deposition (PE-HFCVD). Through two-step processing in an HFCVD reactor, novel nano-structured composite diamond films containing a nanocrystalline diamond layer on the top of a nanocone diamond layer have been synthesized. Well-aligned carbon nanotubes, diamond and graphitic carbon nanocones with controllable alignment orientations have been synthesized by using PE-HFCVD. The orientation of the nanostructures can be controlled by adjusting the working pressure. In a Microwave Plasma Enhanced Chemical Vapor Deposition (MW-PECVD) reactor, high-quality diamond films have been synthesized at low temperatures (310℃-550℃) without adding oxygen or halogen gas in a newly developed processing technique. In this process, carbon source originates from graphite etching, instead of hydrocarbon. The lowest growth temperature for the growth of nanocrystalline diamond films with a reasonable growth rate without addition of oxygen or halogen is 260℃.
