The fabrication of a-C:H films from methane has been performed using dielectric-barrier discharges at atmospheric pressure. The effect of combined-feed gas, such as carbon dioxide, carbon monoxide or acetylene on the ...The fabrication of a-C:H films from methane has been performed using dielectric-barrier discharges at atmospheric pressure. The effect of combined-feed gas, such as carbon dioxide, carbon monoxide or acetylene on the formation of a-C:H films has been investigated. It has been demonstrated that the addition of carbon monoxide or acetylene into methane leads to a remarkable improvement in the fabrication of a-C:H films. The characterization of carbon film obtained has been conducted using FT-IR, Raman and SEM.展开更多
Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique from a mixture of methane, silane and hydrogen, and using diborane and ph...Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique from a mixture of methane, silane and hydrogen, and using diborane and phosphine as doping gases. The effects of changes in the microwave power on the deposition rate and optical bandgap were investigated, and variations in the photoand dark-conductivities and activation energy were studied in conjunction with film analysis using the Raman scattering technique. In the case of boron-doped samples, the conductivity increased rapidly to a maximum, followed by rapid reduction at high microwave power. The ratio of the photo- to dark-conductivity (σph/σd) peaked at microwave power of ~600 W. Under conditions of high microwave power, Raman scattering analysis showed evidence of the formation and increase in the silicon microcrystalline and diamond-like phases in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity.In the case of phosphorusdoped SiC:H samples, it was found that increase in the microwave power has the effect of enhancing the formation of the silicon microcrystalline phase in the films which occurred in correspondence to a rapid increase in the conductivity and reduction in the activation energy The conductivity increase stabilised in samples deposited at microwave power exceeding 500 W probably as a result of dopant saturation. Results from Raman scattering measurements also showed that phosphorus doping had the effect of enhancing the formation of the silicon microcrystals in the film whereas the presence of boron had the effect of preserving the amorphous structure.展开更多
Hydrogenated Cr-incorporated carbon films (Cr/a-C:H) are deposited successfully by using a dc reactive mag- netron sputtering system. The structure and mechanical properties of the as-deposited Cr/a-C:H films are ...Hydrogenated Cr-incorporated carbon films (Cr/a-C:H) are deposited successfully by using a dc reactive mag- netron sputtering system. The structure and mechanical properties of the as-deposited Cr/a-C:H films are characterized systematically by field-emission scanning electron microscope, x-ray diffraction, Raman spectra, nanoindentation and scratch. It is shown that optimal Cr metal forms nanocrystalline carbide to improve the hardness, toughness and adhesion strength in the amorphous carbon matrix, which possesses relatively higher nano-hardness of 15. 7 CPa, elastic modulus of 126.8 GPa and best adhesion strength with critical load (Lc) of 36 N for the Cr/a-C:H film deposited at CH4 flow rate of 20sccm. The friction and wear behaviors of as-deposited Cr/a-C:H films are evaluated under both the ambient air and deionized water conditions. The results reveal that it can achieve superior low friction and anti-wear performance for the Cr/a-C:H film deposited at CH4 flow rate of 20sccm under the ambient air condition, and the friction coetllcient and wear rate tested in deionized water condition are relatively lower compared with those tested under the ambient air condition for each film. Superior combination of mechanical and tribological properties for the Cr/a-C:H film should be a good candidate for engineering applications.展开更多
Boron-doped hydrogenated microcrystalline Germanium (lac-Ge:H) films were deposited by hot-wire CVD. H2 diluted G-ell4 and B2H6 were used as precursors and the substrate temperature was kept at 300 ℃. The properti...Boron-doped hydrogenated microcrystalline Germanium (lac-Ge:H) films were deposited by hot-wire CVD. H2 diluted G-ell4 and B2H6 were used as precursors and the substrate temperature was kept at 300 ℃. The properties of the samples were analyzed by XRD, Raman spectroscopy, Fourier transform infrared spectrometer and Hall Effect measurement with Van der Pauw method. It is found that the films are partially crystallized, with crystalline fractions larger than 45% and grain sizes smaller than 50 nm. The B-doping can enhance the crystallization but reduce the grain sizes, and also enhance the preferential growth of Ge (220). The conductivity of the films increases and tends to be saturated with increasing diborane-to-germane ratio RB2H6. All the Hall mobilities of the samples are larger than 3.8 cmZV-1·s-1. A high conductivity of展开更多
In this paper, a deposition feature of a SiC:H films deposited by a RF sputtering system and a effect on the hardness of the films with various deposition conditions are investigated, and the effects of the silicon...In this paper, a deposition feature of a SiC:H films deposited by a RF sputtering system and a effect on the hardness of the films with various deposition conditions are investigated, and the effects of the silicon on a C:H are studied. It follows from the results that the properties of hardness can be changed with the depositing conditions. An increase of silane in the gas phase allows to deposit a SiC:H having tetrahedral structure. The sets of deposition conditions by which the different types of a SiC:H films can be deposited are obtained.展开更多
Highly conductive boron-doped hydrogenated mieroerystalline silicon (μc-Si:H) films are prepared by very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at the substrate temperatures (Ts)...Highly conductive boron-doped hydrogenated mieroerystalline silicon (μc-Si:H) films are prepared by very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at the substrate temperatures (Ts) ranging from 90℃ to 270℃. The effects of Ts on the growth and properties of the films are investigated. Results indicate that the growth rate, the electrical (dark conductivity, carrier concentration and Hall mobility) and structural (crystallinity and grain size) properties are all strongly dependent on Ts. As Ts increases, it is observed that 1) the growth rate initially increases and then arrives at a maximum value of 13.3 nm/min at Ts=210℃, 2) the crystalline volume fraction (Xc) and the grain size increase initially, then reach their maximum values at TS=140℃, and finally decrease, 3) the dark conductivity (σd), carrier concentration and Hall mobility have a similar dependence on Ts and arrive at their maximum values at Ts-190℃. In addition, it is also observed that at a lower substrate temperature Ts, a higher dopant concentration is required in order to obtain a maximum σd.展开更多
Using diborane as doping gas, p-doped μc-Si:H layers are deposited by using the plasma enhanced chemical vapour deposition (PECVD) technology. The effects of deposition pressure and plasma power on the growth and ...Using diborane as doping gas, p-doped μc-Si:H layers are deposited by using the plasma enhanced chemical vapour deposition (PECVD) technology. The effects of deposition pressure and plasma power on the growth and the properties of μc-Si:H layers are investigated. The results show that the deposition rate, the electrical and the structural properties are all strongly dependent on deposition pressure and plasma power. Boron-doped μc-Si:H films with a dark conductivity as high as 1.42 Ω^-1·cm^-1 and a crystallinity of above 50% are obtained. With this p-layer, μc-Si:H solar cells are fabricated. In addition, the mechanism for the effects of deposition pressure and plasma power on the growth and the properties of boron-doped μc-Si:H layers is discussed.展开更多
Using CH4 and CF4 precursor gases, amorphous fluorinated hydrocarbon (a-C:F:H) films were prepared with the method of microwave electronic cyclotron resonant (ECR) plasma chemical vapor deposition. Deposition rate of ...Using CH4 and CF4 precursor gases, amorphous fluorinated hydrocarbon (a-C:F:H) films were prepared with the method of microwave electronic cyclotron resonant (ECR) plasma chemical vapor deposition. Deposition rate of the film firstly increases and then decreases with variable flow ratios R {[CF4]/([CF4] + [CH4]} due to the competition between deposition and etching process. Results from Fourier-transform infrared transmission spectroscopy of these films show that C-F bond configuration in a-C:F:H films evolves with the variable gas flow ratios R. The locations of the C-F peaks in IR spectra shift to higher frequency with the increase of R, and finally the structure in films with R >75% takes on a PTFE-like structure, which mainly consists of -CF2- chain. The change of optical band gap Eg deduced by a Tauc plot with R is also discussed.展开更多
Hydrogenated amorphous silicon (a-Si:H) films with high and same order of magnitude photosensitivity (-10^5) but different stability were prepared by using microwave electron cyclotron resonance chemical vapour d...Hydrogenated amorphous silicon (a-Si:H) films with high and same order of magnitude photosensitivity (-10^5) but different stability were prepared by using microwave electron cyclotron resonance chemical vapour deposition system under the different deposition conditions. It was proposed that there was no direct correlation between the photosensitivity and the hydrogen content (CH) as well as H-Si bonding configurations, but for the stability, they were the critical factors. The experimental results indicated that higher substrate temperature, hydrogen dilution ratio and lower deposition rate played an important role in improving the microstructure of a-Si:H films. We used hydrogen elimination model to explain our experimental results.展开更多
Hydrogenated silicon (Si:H) thin films for application in solar ceils were deposited by using very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at a substrate temperature of about 170 ℃,...Hydrogenated silicon (Si:H) thin films for application in solar ceils were deposited by using very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at a substrate temperature of about 170 ℃, The electrical, structural, and optical properties of the films were investigated. The deposited films were then applied as i-layers for p-i-n single junction solar cells. The current-voltage (I - V) characteristics of the cells were measured before and after the light soaking. The results suggest that the films deposited near the transition region have an optimum properties for application in solar cells. The cell with an i-layer prepared near the transition region shows the best stable performance.展开更多
Methane (CH4) plasma was used to produce amorphous hydrogenated carbon (a- C:H) films by a single capacitively coupled radio frequency (RF) powered plasma system. The system consists of two parallel electrodes...Methane (CH4) plasma was used to produce amorphous hydrogenated carbon (a- C:H) films by a single capacitively coupled radio frequency (RF) powered plasma system. The system consists of two parallel electrodes: the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy (OES). The structural and optical properties were analyzed via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.展开更多
The effects of different substrates on the structure and hydrogen evolution from a-Si: H thin films deposited by plasma enhanced chemical vapour deposition were studied, as well as the similar films exposed to an hyd...The effects of different substrates on the structure and hydrogen evolution from a-Si: H thin films deposited by plasma enhanced chemical vapour deposition were studied, as well as the similar films exposed to an hydrogen plasma. Spectroscopic ellipsometry and hydrogen evolution measurements were used to analyse the effects of the substrate and hydrogen plasma on the films microstructure, thickness, hydrogen content, hydrogen bonding and hydrogen evolution. The hydrogen evolution spectra show a strong substrate dependence. In particular on crystalline silicon substrate, the formation of bubbles was observed. For different substrates, hydrogen plasma treatments lightly affected the hydrogen evolution spectra. These results indicate that the action of hydrogen in a-Si:H was modified by the nature of the substrate.展开更多
A P^+-nc-Si:H film(boron-doped nc-Si:H thin film) was used as a complex anode of an OLED.As an ideal candidate for the composite anode,the P^+-nc-Si:H thin film has a good conductivity with a high work function...A P^+-nc-Si:H film(boron-doped nc-Si:H thin film) was used as a complex anode of an OLED.As an ideal candidate for the composite anode,the P^+-nc-Si:H thin film has a good conductivity with a high work function(- 5.7 eV) and outstanding optical properties of high reflectivity,transmission,and a very low absorption.As a result,the combination of the relatively high reflectivity of a P^+-nc-Si:H film/ITO complex anode with the very high reflectivity of an Al cathode could form a micro-cavity structure with a certain Q to improve the efficiency of the OLED fabricated on it.An RGB pixel generated by microcavity OLEDs is beneficial for both the reduction of the light loss and the improvement of the color purity and the efficiency.The small molecule Alq would be useful for the emitting light layer(EML) of the MOLED,and the P^+-nc-Si film would be used as a complex anode of the MOLED,whose configuration can be constructed as Glass/LTO/P^+-nc-Si:H/ITO/MoO3/NPB/Alq/LiF/Al.By adjusting the thickness of the organic layer NPB/Alq,the optical length of the microcavity and the REB colors of the device can be obtained.The peak wavelengths of an OLED are located at 486,550,and 608 nm,respectively.The CIE coordinates are(0.21,0.45),(0.33,0.63),and(0.54,0.54),and the full widths at half maximum(FWHM) are 35,32,and 39 nm for red,green,and blue,respectively.展开更多
Hydrogenated nanocrystalline silicon thin films were fabricated from Sill4 with H2 dilution at a low substrate temperature of 200℃ by the conventional plasma enhanced chemical vapor deposition technique. A high depos...Hydrogenated nanocrystalline silicon thin films were fabricated from Sill4 with H2 dilution at a low substrate temperature of 200℃ by the conventional plasma enhanced chemical vapor deposition technique. A high deposition rate over 0.75 nm/s can be achieved. Raman scattering spectral measurements revealed that the crystalline fraction and grain size increased with the increase in hydrogen dilution ratio. Fourier transform infrared spectrum measurements showed that the hydrogen content decreased and the Si-H bonding configuration changed mainly from Sill to Sill2 with the increase in hydrogen dilution ratio. This suggested that the hydrogen dilution played an important role in the low-temperature growth of nanocrystalline silicon thin film. The growth mechanism is discussed in terms of a surface diffusion model and hydrogen etching effects.展开更多
Monte Carlo simulations are adopted to study the electron motion in the mixture of H2 and CH4 during diamond synthesis via Glow Plasma-assisted Chemical Vapor Deposition (GPCVD). The non-uniform electric field is used...Monte Carlo simulations are adopted to study the electron motion in the mixture of H2 and CH4 during diamond synthesis via Glow Plasma-assisted Chemical Vapor Deposition (GPCVD). The non-uniform electric field is used and the avalanche of electrons is taken into account in this simulation. The average energy distribution of electrons and the space distribution of effective species such as CH3, CH+3, CH+ and H at various gas pressures are given in this paper, and optimum experimental conditions are inferred from these results.展开更多
Phosphorous-doped hydrogenated nanocrystalline silicon oxide (n-nc-SiOx:H) films are prepared via radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). Increasing deposition power during n-nc-SiOx...Phosphorous-doped hydrogenated nanocrystalline silicon oxide (n-nc-SiOx:H) films are prepared via radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). Increasing deposition power during n-nc-SiOx:H film growth process can enhance the formation of nanocrystalline and obtain a uniform microstructure of n-nc-SiOx:H film. In addition, in 20s interval before increasing the deposition power, high density small grains are formed in amorphous SiOx matrix with higher crystalline volume fraction (Ic) and have a lower lateral conductivity. This uniform microstructure indicates that the higher Ic can leads to better vertical conductivity, lower refractive index, wider optical band-gap. It improves the back reflection in a-Si:H/a-SiGe:H tandem solar cells acting as an n-nc-SiOx:H back reflector prepared by the gradient power during deposition. Compared with the sample with SiOx back reflector, with a constant power used in deposition process, the sample with gradient power SiOx back reflector can enhance the total short-circuit current density (Jsc) and the initial efficiency of a-Si:H/a-SiGe:H tandem solar cells by 8.3% and 15.5%, respectively.展开更多
A new preparing technology, very high frequency plasma assisted reactive thermal chemical vapour deposition (VHFPA-RTCVD), is introduced to prepare SiGe:H thin films on substrate kept at a lower temperature. In the...A new preparing technology, very high frequency plasma assisted reactive thermal chemical vapour deposition (VHFPA-RTCVD), is introduced to prepare SiGe:H thin films on substrate kept at a lower temperature. In the previous work, reactive thermal chemical vapour deposition (I^TCVD) technology was successfully used to prepare SiGe:H thin films, but the temperature of the substrate needed to exceed 400℃. In this work, very high frequency plasma method is used to assist RTCVD technology in reducing the temperature of substrate by largely enhancing the temperature of reacting gases on the surface of the substrate. The growth rate, structural properties, surface morphology, photo- conductivity and dark-conductivity of SiGe:H thin films prepared by this new technology are investigated for films with different germanium concentrations, and the experimental results are discussed.展开更多
Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated bod...Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated body fluid are investigated.The results show the concentration of Ag first decreases and then increases with the modulation period decreasing from 984 nm to 250 nm.Whereas the C content has an opposite variation trend.Notably,the concentration of Ag plays a more important role than the modulation period in the properties of the multilayer film.The a-C:H sublayer of the film with an appropriate Ag concentration(8.97 at.%)(modulation period of 512 nm)maintains the highest sp3/sp2 ratio,surface roughness and hardness,and excellent tribological property in the stimulated body fluid.An appropriate number of Ag atoms and size of Ag atom allow the Ag atoms to easily enter into the contact interface for load bearing and lubricating.This work proves that the Ag nanoparticles in the a-C:H sublayer plays a more important role in the tribological properties of the composite-multilayer film in stimulated body fluid condition.展开更多
This paper found that the crystalline volume ratio (Xc) of μc-Si deposited on SiNx substrate is higher than that on 7059 glass. At the same silane concentration (SC) (for example, at SC=2%), the Xc of μc-Si de...This paper found that the crystalline volume ratio (Xc) of μc-Si deposited on SiNx substrate is higher than that on 7059 glass. At the same silane concentration (SC) (for example, at SC=2%), the Xc of μc-Si deposited on SiNx is more than 64%, but just 44% if deposited on Conning 7059. It considered that the ‘hills' on SiNx substrate would promote the crystalline growth of μc-Si thin film, which has been confirmed by atomic force microscope (AFM) observation. Comparing several thin film transistor (TFT) samples whose active-layer were deposited under various SC, this paper found that the appropriate SC for the μc-Si thin film used in TFT as active layer should be more than 2%, and Xc should be around 50%. Additionally, the stability comparison of μc-Si TFT and a-Si TFT is shown in this paper.展开更多
Hydrogenated microcrystalline silicon (μcSi:H) thin films were deposited by an radio frequency (RF)(13.56 MHz) magnetron sputtering at different substrate temperatures (100–300℃), and the influences of substrate te...Hydrogenated microcrystalline silicon (μcSi:H) thin films were deposited by an radio frequency (RF)(13.56 MHz) magnetron sputtering at different substrate temperatures (100–300℃), and the influences of substrate temperature on the growth and properties ofμc-Si:H thin films were investigated. Surface roughness and crystallinity of the thin films increase as substrate temperature increases. And all thin films are at the transition region(X_(c)=49.2%~61.0%). Theμc-Si:H thin films deposited at lower substrate temperature (≤200℃) represent a weak(220) preferred orientation, while the thin films deposited at higher substrate temperature (≥250℃) exhibit a weak(111) preferred orientation. The μc-Si:H thin films have a dense structure, and the structural compactness of the thin films slightly increases with substrate temperature increasing. The Fourier transform infrared spectroscopy (FTIR) results indicate that theμc-Si:H thin films have a low hydrogen content (3.9 at%–5.6 at%), which is in favor of reducing light-induced degradation effect.展开更多
基金The project supported by the Key Foundation of Tianjin City Committee of Science Technology and ABB Corporate Research Ltd., Switzerland
文摘The fabrication of a-C:H films from methane has been performed using dielectric-barrier discharges at atmospheric pressure. The effect of combined-feed gas, such as carbon dioxide, carbon monoxide or acetylene on the formation of a-C:H films has been investigated. It has been demonstrated that the addition of carbon monoxide or acetylene into methane leads to a remarkable improvement in the fabrication of a-C:H films. The characterization of carbon film obtained has been conducted using FT-IR, Raman and SEM.
文摘Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique from a mixture of methane, silane and hydrogen, and using diborane and phosphine as doping gases. The effects of changes in the microwave power on the deposition rate and optical bandgap were investigated, and variations in the photoand dark-conductivities and activation energy were studied in conjunction with film analysis using the Raman scattering technique. In the case of boron-doped samples, the conductivity increased rapidly to a maximum, followed by rapid reduction at high microwave power. The ratio of the photo- to dark-conductivity (σph/σd) peaked at microwave power of ~600 W. Under conditions of high microwave power, Raman scattering analysis showed evidence of the formation and increase in the silicon microcrystalline and diamond-like phases in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity.In the case of phosphorusdoped SiC:H samples, it was found that increase in the microwave power has the effect of enhancing the formation of the silicon microcrystalline phase in the films which occurred in correspondence to a rapid increase in the conductivity and reduction in the activation energy The conductivity increase stabilised in samples deposited at microwave power exceeding 500 W probably as a result of dopant saturation. Results from Raman scattering measurements also showed that phosphorus doping had the effect of enhancing the formation of the silicon microcrystals in the film whereas the presence of boron had the effect of preserving the amorphous structure.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51302116 and 51365016the Open Fund Item of State Key Laboratory of Solid Lubrication of Lanzhou Institute of Chemical Physics of Chinese Academy of Sciences under Grant No LSL-1203
文摘Hydrogenated Cr-incorporated carbon films (Cr/a-C:H) are deposited successfully by using a dc reactive mag- netron sputtering system. The structure and mechanical properties of the as-deposited Cr/a-C:H films are characterized systematically by field-emission scanning electron microscope, x-ray diffraction, Raman spectra, nanoindentation and scratch. It is shown that optimal Cr metal forms nanocrystalline carbide to improve the hardness, toughness and adhesion strength in the amorphous carbon matrix, which possesses relatively higher nano-hardness of 15. 7 CPa, elastic modulus of 126.8 GPa and best adhesion strength with critical load (Lc) of 36 N for the Cr/a-C:H film deposited at CH4 flow rate of 20sccm. The friction and wear behaviors of as-deposited Cr/a-C:H films are evaluated under both the ambient air and deionized water conditions. The results reveal that it can achieve superior low friction and anti-wear performance for the Cr/a-C:H film deposited at CH4 flow rate of 20sccm under the ambient air condition, and the friction coetllcient and wear rate tested in deionized water condition are relatively lower compared with those tested under the ambient air condition for each film. Superior combination of mechanical and tribological properties for the Cr/a-C:H film should be a good candidate for engineering applications.
基金Funded by the National High-tech Research and Development Program of China(863 Program)(No.2006AA03Z219)Graduate Innovation Plan of Nanjing University of Aeronautics and Astronautics(No.BCXJ08-10)the National Natural Science Foundation of China(No.61306084)
文摘Boron-doped hydrogenated microcrystalline Germanium (lac-Ge:H) films were deposited by hot-wire CVD. H2 diluted G-ell4 and B2H6 were used as precursors and the substrate temperature was kept at 300 ℃. The properties of the samples were analyzed by XRD, Raman spectroscopy, Fourier transform infrared spectrometer and Hall Effect measurement with Van der Pauw method. It is found that the films are partially crystallized, with crystalline fractions larger than 45% and grain sizes smaller than 50 nm. The B-doping can enhance the crystallization but reduce the grain sizes, and also enhance the preferential growth of Ge (220). The conductivity of the films increases and tends to be saturated with increasing diborane-to-germane ratio RB2H6. All the Hall mobilities of the samples are larger than 3.8 cmZV-1·s-1. A high conductivity of
文摘In this paper, a deposition feature of a SiC:H films deposited by a RF sputtering system and a effect on the hardness of the films with various deposition conditions are investigated, and the effects of the silicon on a C:H are studied. It follows from the results that the properties of hardness can be changed with the depositing conditions. An increase of silane in the gas phase allows to deposit a SiC:H having tetrahedral structure. The sets of deposition conditions by which the different types of a SiC:H films can be deposited are obtained.
文摘Highly conductive boron-doped hydrogenated mieroerystalline silicon (μc-Si:H) films are prepared by very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at the substrate temperatures (Ts) ranging from 90℃ to 270℃. The effects of Ts on the growth and properties of the films are investigated. Results indicate that the growth rate, the electrical (dark conductivity, carrier concentration and Hall mobility) and structural (crystallinity and grain size) properties are all strongly dependent on Ts. As Ts increases, it is observed that 1) the growth rate initially increases and then arrives at a maximum value of 13.3 nm/min at Ts=210℃, 2) the crystalline volume fraction (Xc) and the grain size increase initially, then reach their maximum values at TS=140℃, and finally decrease, 3) the dark conductivity (σd), carrier concentration and Hall mobility have a similar dependence on Ts and arrive at their maximum values at Ts-190℃. In addition, it is also observed that at a lower substrate temperature Ts, a higher dopant concentration is required in order to obtain a maximum σd.
基金Project supported by the State Key Development Program for Basic Research of China (Grant No 2006CB202601)Basic Research Project of Henan province,China (Grant No 072300410140)
文摘Using diborane as doping gas, p-doped μc-Si:H layers are deposited by using the plasma enhanced chemical vapour deposition (PECVD) technology. The effects of deposition pressure and plasma power on the growth and the properties of μc-Si:H layers are investigated. The results show that the deposition rate, the electrical and the structural properties are all strongly dependent on deposition pressure and plasma power. Boron-doped μc-Si:H films with a dark conductivity as high as 1.42 Ω^-1·cm^-1 and a crystallinity of above 50% are obtained. With this p-layer, μc-Si:H solar cells are fabricated. In addition, the mechanism for the effects of deposition pressure and plasma power on the growth and the properties of boron-doped μc-Si:H layers is discussed.
基金The project supported by the National Nature Science Foundation of China (No. 10305008)
文摘Using CH4 and CF4 precursor gases, amorphous fluorinated hydrocarbon (a-C:F:H) films were prepared with the method of microwave electronic cyclotron resonant (ECR) plasma chemical vapor deposition. Deposition rate of the film firstly increases and then decreases with variable flow ratios R {[CF4]/([CF4] + [CH4]} due to the competition between deposition and etching process. Results from Fourier-transform infrared transmission spectroscopy of these films show that C-F bond configuration in a-C:F:H films evolves with the variable gas flow ratios R. The locations of the C-F peaks in IR spectra shift to higher frequency with the increase of R, and finally the structure in films with R >75% takes on a PTFE-like structure, which mainly consists of -CF2- chain. The change of optical band gap Eg deduced by a Tauc plot with R is also discussed.
文摘Hydrogenated amorphous silicon (a-Si:H) films with high and same order of magnitude photosensitivity (-10^5) but different stability were prepared by using microwave electron cyclotron resonance chemical vapour deposition system under the different deposition conditions. It was proposed that there was no direct correlation between the photosensitivity and the hydrogen content (CH) as well as H-Si bonding configurations, but for the stability, they were the critical factors. The experimental results indicated that higher substrate temperature, hydrogen dilution ratio and lower deposition rate played an important role in improving the microstructure of a-Si:H films. We used hydrogen elimination model to explain our experimental results.
文摘Hydrogenated silicon (Si:H) thin films for application in solar ceils were deposited by using very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at a substrate temperature of about 170 ℃, The electrical, structural, and optical properties of the films were investigated. The deposited films were then applied as i-layers for p-i-n single junction solar cells. The current-voltage (I - V) characteristics of the cells were measured before and after the light soaking. The results suggest that the films deposited near the transition region have an optimum properties for application in solar cells. The cell with an i-layer prepared near the transition region shows the best stable performance.
基金supported by the Scientific Research Project Fund of Duzce University under the projectnumber 2013.05.02.195
文摘Methane (CH4) plasma was used to produce amorphous hydrogenated carbon (a- C:H) films by a single capacitively coupled radio frequency (RF) powered plasma system. The system consists of two parallel electrodes: the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy (OES). The structural and optical properties were analyzed via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.
文摘The effects of different substrates on the structure and hydrogen evolution from a-Si: H thin films deposited by plasma enhanced chemical vapour deposition were studied, as well as the similar films exposed to an hydrogen plasma. Spectroscopic ellipsometry and hydrogen evolution measurements were used to analyse the effects of the substrate and hydrogen plasma on the films microstructure, thickness, hydrogen content, hydrogen bonding and hydrogen evolution. The hydrogen evolution spectra show a strong substrate dependence. In particular on crystalline silicon substrate, the formation of bubbles was observed. For different substrates, hydrogen plasma treatments lightly affected the hydrogen evolution spectra. These results indicate that the action of hydrogen in a-Si:H was modified by the nature of the substrate.
基金supported by the National High Technology Research and Development Program of China(No.2004AA303570)the National Natural Science Foundation of China (No. 60437030)
文摘A P^+-nc-Si:H film(boron-doped nc-Si:H thin film) was used as a complex anode of an OLED.As an ideal candidate for the composite anode,the P^+-nc-Si:H thin film has a good conductivity with a high work function(- 5.7 eV) and outstanding optical properties of high reflectivity,transmission,and a very low absorption.As a result,the combination of the relatively high reflectivity of a P^+-nc-Si:H film/ITO complex anode with the very high reflectivity of an Al cathode could form a micro-cavity structure with a certain Q to improve the efficiency of the OLED fabricated on it.An RGB pixel generated by microcavity OLEDs is beneficial for both the reduction of the light loss and the improvement of the color purity and the efficiency.The small molecule Alq would be useful for the emitting light layer(EML) of the MOLED,and the P^+-nc-Si film would be used as a complex anode of the MOLED,whose configuration can be constructed as Glass/LTO/P^+-nc-Si:H/ITO/MoO3/NPB/Alq/LiF/Al.By adjusting the thickness of the organic layer NPB/Alq,the optical length of the microcavity and the REB colors of the device can be obtained.The peak wavelengths of an OLED are located at 486,550,and 608 nm,respectively.The CIE coordinates are(0.21,0.45),(0.33,0.63),and(0.54,0.54),and the full widths at half maximum(FWHM) are 35,32,and 39 nm for red,green,and blue,respectively.
基金supported by the Major State Basic Research and Development Program of China,Ministry of Science and Technology of China (No.G2000028208)
文摘Hydrogenated nanocrystalline silicon thin films were fabricated from Sill4 with H2 dilution at a low substrate temperature of 200℃ by the conventional plasma enhanced chemical vapor deposition technique. A high deposition rate over 0.75 nm/s can be achieved. Raman scattering spectral measurements revealed that the crystalline fraction and grain size increased with the increase in hydrogen dilution ratio. Fourier transform infrared spectrum measurements showed that the hydrogen content decreased and the Si-H bonding configuration changed mainly from Sill to Sill2 with the increase in hydrogen dilution ratio. This suggested that the hydrogen dilution played an important role in the low-temperature growth of nanocrystalline silicon thin film. The growth mechanism is discussed in terms of a surface diffusion model and hydrogen etching effects.
基金This work was supported by Doctor Foundation of Hebei Education Committee Hebei Natural Science Foundation(599091 ) of China
文摘Monte Carlo simulations are adopted to study the electron motion in the mixture of H2 and CH4 during diamond synthesis via Glow Plasma-assisted Chemical Vapor Deposition (GPCVD). The non-uniform electric field is used and the avalanche of electrons is taken into account in this simulation. The average energy distribution of electrons and the space distribution of effective species such as CH3, CH+3, CH+ and H at various gas pressures are given in this paper, and optimum experimental conditions are inferred from these results.
基金supported by the Hi-Tech Research and Development Program of China(Grant No.2013AA050302)the National Natural Science Foundation of China(Grant No.61474065)+2 种基金Tianjin Municipal Research Key Program of Application Foundation and Advanced Technology,China(Grant No.15JCZDJC31300)the Key Project in the Science&Technology Pillar Program of Jiangsu Province,China(Grant No.BE2014147-3)the Specialized Research Fund for the Ph.D.Program of Higher Education,China(Grant No.20120031110039)
文摘Phosphorous-doped hydrogenated nanocrystalline silicon oxide (n-nc-SiOx:H) films are prepared via radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). Increasing deposition power during n-nc-SiOx:H film growth process can enhance the formation of nanocrystalline and obtain a uniform microstructure of n-nc-SiOx:H film. In addition, in 20s interval before increasing the deposition power, high density small grains are formed in amorphous SiOx matrix with higher crystalline volume fraction (Ic) and have a lower lateral conductivity. This uniform microstructure indicates that the higher Ic can leads to better vertical conductivity, lower refractive index, wider optical band-gap. It improves the back reflection in a-Si:H/a-SiGe:H tandem solar cells acting as an n-nc-SiOx:H back reflector prepared by the gradient power during deposition. Compared with the sample with SiOx back reflector, with a constant power used in deposition process, the sample with gradient power SiOx back reflector can enhance the total short-circuit current density (Jsc) and the initial efficiency of a-Si:H/a-SiGe:H tandem solar cells by 8.3% and 15.5%, respectively.
基金supported by the State Key Development Program for Basic Research of China (Grant Nos 2006CB202602 and 2006CB202603)the Tianjin Research Foundation for Basic Research,China (Grant No 08JCZDJC 22200)International Cooperative Project of the Ministry of Science and Technology,China (Grant No 2006DFA62390)
文摘A new preparing technology, very high frequency plasma assisted reactive thermal chemical vapour deposition (VHFPA-RTCVD), is introduced to prepare SiGe:H thin films on substrate kept at a lower temperature. In the previous work, reactive thermal chemical vapour deposition (I^TCVD) technology was successfully used to prepare SiGe:H thin films, but the temperature of the substrate needed to exceed 400℃. In this work, very high frequency plasma method is used to assist RTCVD technology in reducing the temperature of substrate by largely enhancing the temperature of reacting gases on the surface of the substrate. The growth rate, structural properties, surface morphology, photo- conductivity and dark-conductivity of SiGe:H thin films prepared by this new technology are investigated for films with different germanium concentrations, and the experimental results are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51801133,51505318,and 51671140)the Science and Technology Major Project of Shanxi Province,China(Grant No.20181102013)+1 种基金the Shanxi Provincial Youth Fund,China(Grant No.201801D221135)the“1331 Project”Engineering Research Center of Shanxi Province,China(Grant No.PT201801).
文摘Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated body fluid are investigated.The results show the concentration of Ag first decreases and then increases with the modulation period decreasing from 984 nm to 250 nm.Whereas the C content has an opposite variation trend.Notably,the concentration of Ag plays a more important role than the modulation period in the properties of the multilayer film.The a-C:H sublayer of the film with an appropriate Ag concentration(8.97 at.%)(modulation period of 512 nm)maintains the highest sp3/sp2 ratio,surface roughness and hardness,and excellent tribological property in the stimulated body fluid.An appropriate number of Ag atoms and size of Ag atom allow the Ag atoms to easily enter into the contact interface for load bearing and lubricating.This work proves that the Ag nanoparticles in the a-C:H sublayer plays a more important role in the tribological properties of the composite-multilayer film in stimulated body fluid condition.
基金Project supported by the ‘863' Project of National Ministry of Science and Technology (Grant No 2004AA33570), Key Project of NSFC (Grant No 60437030) and Tianjin Natural Science Foundation (Grant No 05YFJMJC01400).
文摘This paper found that the crystalline volume ratio (Xc) of μc-Si deposited on SiNx substrate is higher than that on 7059 glass. At the same silane concentration (SC) (for example, at SC=2%), the Xc of μc-Si deposited on SiNx is more than 64%, but just 44% if deposited on Conning 7059. It considered that the ‘hills' on SiNx substrate would promote the crystalline growth of μc-Si thin film, which has been confirmed by atomic force microscope (AFM) observation. Comparing several thin film transistor (TFT) samples whose active-layer were deposited under various SC, this paper found that the appropriate SC for the μc-Si thin film used in TFT as active layer should be more than 2%, and Xc should be around 50%. Additionally, the stability comparison of μc-Si TFT and a-Si TFT is shown in this paper.
基金financially supported by the Young Scientists Fund of the National Natural Science Foundation of China (No. 61106096)the Natural Science Foundation of Ningbo, China (No. 2012A610120)。
文摘Hydrogenated microcrystalline silicon (μcSi:H) thin films were deposited by an radio frequency (RF)(13.56 MHz) magnetron sputtering at different substrate temperatures (100–300℃), and the influences of substrate temperature on the growth and properties ofμc-Si:H thin films were investigated. Surface roughness and crystallinity of the thin films increase as substrate temperature increases. And all thin films are at the transition region(X_(c)=49.2%~61.0%). Theμc-Si:H thin films deposited at lower substrate temperature (≤200℃) represent a weak(220) preferred orientation, while the thin films deposited at higher substrate temperature (≥250℃) exhibit a weak(111) preferred orientation. The μc-Si:H thin films have a dense structure, and the structural compactness of the thin films slightly increases with substrate temperature increasing. The Fourier transform infrared spectroscopy (FTIR) results indicate that theμc-Si:H thin films have a low hydrogen content (3.9 at%–5.6 at%), which is in favor of reducing light-induced degradation effect.