Optical absorption of Ar and H ion beam irradiated multi-walled carbon nanotube (MWCNT) sheets at various doses in the visible and terahertz spectral ranges was investigated.It was found that the optical absorption of...Optical absorption of Ar and H ion beam irradiated multi-walled carbon nanotube (MWCNT) sheets at various doses in the visible and terahertz spectral ranges was investigated.It was found that the optical absorption of MWCNT sheets in the visible range was decreased with increasing ion irradiation dose.Similar behavior was observed in terahertz range,where the optical absorption of MWCNT sheets in the range of 0 to 1.5 THz was also decreased with increasing ion irradiation dose.The optical absorption decreases in irradiated MWCNT sheets can be ascribed to the increase of defects in the irradiated MWCNTs.展开更多
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
An effective method by low energy carbonhydrogen ion treatment to enhance field emission of the carbon nanotubes (CNTs) is demonstrated. Comparing with control, field emission (FE) currents of the CNTs by carbonhydrog...An effective method by low energy carbonhydrogen ion treatment to enhance field emission of the carbon nanotubes (CNTs) is demonstrated. Comparing with control, field emission (FE) currents of the CNTs by carbonhydrogen ion irradiation increased, and the turn-on field and the threshold field decreased significantly. The structure characteristic revealed by transmission electron microscopy demonstrates that CNTs are coated by nano-graphite particles after being treated with low energy carbonhydrogen ion and that there are large quantities of defects and grain boundaries in the coated layer. It is considered that the coating layer can decrease the effective surface work function of CNTs and correspondingly increase field emission. In addition, the defects, the grain boundaries and the C-H dipoles forming in the process of the low energy ions irradiation can effectively enhance the field emission.展开更多
Multi-walled carbon nanotubes were irradiated with 40 keV Si ion beam to a dose of 1×1017 cm-2. The multiple-way carbon nanowire junctions and the Si doping in carbon nanowires were realized. Moreover, the forma-...Multi-walled carbon nanotubes were irradiated with 40 keV Si ion beam to a dose of 1×1017 cm-2. The multiple-way carbon nanowire junctions and the Si doping in carbon nanowires were realized. Moreover, the forma- tion processes of carbon nanowire junctions and the corresponding mechanism were studied.展开更多
In a traditional hot-filament chemical vapor deposition (HF-CVD) system, highly (111)-textured diamond film was deposited on Si (111) substrate treated by diamond powder ultrasonic scratching or other methods. The rel...In a traditional hot-filament chemical vapor deposition (HF-CVD) system, highly (111)-textured diamond film was deposited on Si (111) substrate treated by diamond powder ultrasonic scratching or other methods. The relationship between the (111)-textured diamond film growth and the nucleation density has been discussed. The morphologies and structures of the films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy.展开更多
The question of whether ion beam analysis technique can be applied to the study of polymers has been investigated.Degradation of mylar foil under MeV ion beam irradiation was observed.In order to describe the degradat...The question of whether ion beam analysis technique can be applied to the study of polymers has been investigated.Degradation of mylar foil under MeV ion beam irradiation was observed.In order to describe the degradation process of mylar foil under ion beam irradiation quantitatively,only one dose-independent degradation cross section for each of hydrogen and oxygen was needed.Our results suggest that proton or He^(+) ion combined with rotation of the target(scanning area of 20mm^(2))can be used to study the mylar foil without substantially changing the compositions of the target up to ion fluence 5 × 10^(15)/cm^(2).展开更多
基金Supported by Chinese Academy of Sciences Knowledge Innovation Program(No.KJCX3.SYW.N10)National Natural Science Foundation of China(No.10775171)
文摘Optical absorption of Ar and H ion beam irradiated multi-walled carbon nanotube (MWCNT) sheets at various doses in the visible and terahertz spectral ranges was investigated.It was found that the optical absorption of MWCNT sheets in the visible range was decreased with increasing ion irradiation dose.Similar behavior was observed in terahertz range,where the optical absorption of MWCNT sheets in the range of 0 to 1.5 THz was also decreased with increasing ion irradiation dose.The optical absorption decreases in irradiated MWCNT sheets can be ascribed to the increase of defects in the irradiated MWCNTs.
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a Key Program of the Knowledge Innovation Project of Chinese Academy of Sciences, National Natural Science Foundation of China (Grant No.10375085)National Basic Research Program of China (Grant No.2003CB716901)
文摘An effective method by low energy carbonhydrogen ion treatment to enhance field emission of the carbon nanotubes (CNTs) is demonstrated. Comparing with control, field emission (FE) currents of the CNTs by carbonhydrogen ion irradiation increased, and the turn-on field and the threshold field decreased significantly. The structure characteristic revealed by transmission electron microscopy demonstrates that CNTs are coated by nano-graphite particles after being treated with low energy carbonhydrogen ion and that there are large quantities of defects and grain boundaries in the coated layer. It is considered that the coating layer can decrease the effective surface work function of CNTs and correspondingly increase field emission. In addition, the defects, the grain boundaries and the C-H dipoles forming in the process of the low energy ions irradiation can effectively enhance the field emission.
基金Supported by the National Natural Science Foundation of China (Grant No.10375085)the Chinese Academy of Sciences Knowledge Innovation Pro-gram (Grant No. KJCX3.SYW.N10).
文摘Multi-walled carbon nanotubes were irradiated with 40 keV Si ion beam to a dose of 1×1017 cm-2. The multiple-way carbon nanowire junctions and the Si doping in carbon nanowires were realized. Moreover, the forma- tion processes of carbon nanowire junctions and the corresponding mechanism were studied.
基金Sthe Key Project of Chinese Academy of Sciences Knowledge Innovation Program (Grant No. KJCX3. SYW. N10)
文摘In a traditional hot-filament chemical vapor deposition (HF-CVD) system, highly (111)-textured diamond film was deposited on Si (111) substrate treated by diamond powder ultrasonic scratching or other methods. The relationship between the (111)-textured diamond film growth and the nucleation density has been discussed. The morphologies and structures of the films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy.
文摘The question of whether ion beam analysis technique can be applied to the study of polymers has been investigated.Degradation of mylar foil under MeV ion beam irradiation was observed.In order to describe the degradation process of mylar foil under ion beam irradiation quantitatively,only one dose-independent degradation cross section for each of hydrogen and oxygen was needed.Our results suggest that proton or He^(+) ion combined with rotation of the target(scanning area of 20mm^(2))can be used to study the mylar foil without substantially changing the compositions of the target up to ion fluence 5 × 10^(15)/cm^(2).
