The structural evolution and optical characterization of hydrogenated silicon(Si:H) thin films obtained by conventional radio frequency(RF) plasma enhanced chemical vapor deposition(PECVD) through decomposition of sil...The structural evolution and optical characterization of hydrogenated silicon(Si:H) thin films obtained by conventional radio frequency(RF) plasma enhanced chemical vapor deposition(PECVD) through decomposition of silane diluted with argon were studied by X-ray diffractometry(XRD),Fourier transform infrared(FTIR) spectroscopy,Raman spectroscopy,transmission electron microscopy(TEM),and ultraviolet and visible(UV-vis) spectroscopy,respectively.The influence of argon dilution on the optical properties of the thin films was also studied.It is found that argon as dilution gas plays a significant role in the growth of nano-crystal grains and amorphous network in Si:H thin films.The structural evolution of the thin films with different argon dilution ratios is observed and it is suggested that argon plasma leads to the nanocrystallization in the thin films during the deposition process.The nanocrystallization initiating at a relatively low dilution ratio is also observed.With the increase of argon portion in the mixed precursor gases,nano-crystal grains in the thin films evolve regularly.The structural evolution is explained by a proposed model based on the energy exchange between the argon plasma constituted with Ar* and Ar+ radicals and the growth regions of the thin films.It is observed that both the absorption of UV-vis light and the optical gap decrease with the increase of dilution ratio.展开更多
Abstract： An effective approach was conducted for estimating fracture toughness using the crack opening displacement （COD） method for plasma enhanced chemical vapor deposition （PECVD） coating materials. For this ...Abstract： An effective approach was conducted for estimating fracture toughness using the crack opening displacement （COD） method for plasma enhanced chemical vapor deposition （PECVD） coating materials. For this evaluation, an elastoplastic analysis was used to estimate critical COD values for single edge notched bending （SENB） specimens. The relationship between fracture toughness （Kic） and critical COD for SENB specimens was obtained. Microstructure of the interface between AleO3-TiO2 composite ceramic coatings and AISI 1045 steel substrates was studied by using scanning electron microscope （SEM）. Chemical compositions were clarified by energy-dispersive X-ray spectroscopy （EDS）. The results show that the interface between of Al203-TiO2 and substrate has mechanical combining. The nanohardness of the coatings can reach 1 200 GPa examined by nanoindentation. The Klc was calculated according to this relationship from critical COD. The bending process produces a significant relationship of COD independent of the axial force applied. Fractographic analysis was conducted to determine the crack length. From the physical analysis of nanoindentation curves, the elastic modulus of 1045/AI2O3-TiO2 is 180 GPa for the 50 μm film. The highest value of fracture toughness for 1045/A1203-TiO2-250 μm is 348 MPa·mv2.展开更多
基金Project(60425101) supported by the National Outstanding Young Scientists Foundation of ChinaProject(06DZ0241) supported by the Science Foundation of General Armament Department of China
文摘The structural evolution and optical characterization of hydrogenated silicon(Si:H) thin films obtained by conventional radio frequency(RF) plasma enhanced chemical vapor deposition(PECVD) through decomposition of silane diluted with argon were studied by X-ray diffractometry(XRD),Fourier transform infrared(FTIR) spectroscopy,Raman spectroscopy,transmission electron microscopy(TEM),and ultraviolet and visible(UV-vis) spectroscopy,respectively.The influence of argon dilution on the optical properties of the thin films was also studied.It is found that argon as dilution gas plays a significant role in the growth of nano-crystal grains and amorphous network in Si:H thin films.The structural evolution of the thin films with different argon dilution ratios is observed and it is suggested that argon plasma leads to the nanocrystallization in the thin films during the deposition process.The nanocrystallization initiating at a relatively low dilution ratio is also observed.With the increase of argon portion in the mixed precursor gases,nano-crystal grains in the thin films evolve regularly.The structural evolution is explained by a proposed model based on the energy exchange between the argon plasma constituted with Ar* and Ar+ radicals and the growth regions of the thin films.It is observed that both the absorption of UV-vis light and the optical gap decrease with the increase of dilution ratio.
基金Project supported by the National Research Foundation of Korea(2011-0030804)the Korea Research Foundation(KRF2009-0076450)funded by the Korea Government(MEST)
文摘Abstract： An effective approach was conducted for estimating fracture toughness using the crack opening displacement （COD） method for plasma enhanced chemical vapor deposition （PECVD） coating materials. For this evaluation, an elastoplastic analysis was used to estimate critical COD values for single edge notched bending （SENB） specimens. The relationship between fracture toughness （Kic） and critical COD for SENB specimens was obtained. Microstructure of the interface between AleO3-TiO2 composite ceramic coatings and AISI 1045 steel substrates was studied by using scanning electron microscope （SEM）. Chemical compositions were clarified by energy-dispersive X-ray spectroscopy （EDS）. The results show that the interface between of Al203-TiO2 and substrate has mechanical combining. The nanohardness of the coatings can reach 1 200 GPa examined by nanoindentation. The Klc was calculated according to this relationship from critical COD. The bending process produces a significant relationship of COD independent of the axial force applied. Fractographic analysis was conducted to determine the crack length. From the physical analysis of nanoindentation curves, the elastic modulus of 1045/AI2O3-TiO2 is 180 GPa for the 50 μm film. The highest value of fracture toughness for 1045/A1203-TiO2-250 μm is 348 MPa·mv2.
