Hydrogenated amorphous silicon (a-Si: H) films were deposited on Si (100) and glass substrates by dielectric barrier discharge enhanced chemical vapour deposition (DBD-CVD) in (SiH4+H2) atmosphere at room te...Hydrogenated amorphous silicon (a-Si: H) films were deposited on Si (100) and glass substrates by dielectric barrier discharge enhanced chemical vapour deposition (DBD-CVD) in (SiH4+H2) atmosphere at room temperature. Results of the thickness measurement, SEM (scanning electron microscope), Raman, and FTIR (Fourier transform infrared spectroscopy) show that with the increase in the applied peak voltage, the deposition rate and network order of the films increase, and the hydrogen bonding configurations mainly in di-hydrogen (Si-H2) and poly hydrogen (SiH2)n are introduced into the films. The UV-visible transmission spectra show that with the decrease in SiH4/ (SiHn+H2) the thin films' band gap shifts from 1.92 eV to 2.17 eV. These experimental results are in agreement with the theoretic analysis of the DBD discharge. The deposition of a-Si: H films by the DBD-CVD method as reported here for the first time is attractive because it allows fast deposition of a-Si: H films on large-area low-melting-point substrates and requires only a low cost of production without additional heating or pumping equipment.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
Influence of the parameters of plasma enhanced chemical vapor deposition (PECVD) on the surface morphology of hydrogenated amorphous silicon (α-Si:H) film was investigated. The root-mean-square (RMS) roughness...Influence of the parameters of plasma enhanced chemical vapor deposition (PECVD) on the surface morphology of hydrogenated amorphous silicon (α-Si:H) film was investigated. The root-mean-square (RMS) roughness of the film was measured by atomic force microscope (AFM) and the relevant results were analyzed using the surface smoothing mechanism of film deposition. It is shown that an α-Si:H film with smooth surface morphology can be obtained by increasing the PH3/N2 gas flow rate for 10% in a high frequency (HF) mode. For high power, however, the surface morphology of the film will deteriorate when the Sill4 gas flow rate increases. Furthermore, optimized parameters of PECVD for growing the film with smooth surface were obtained to be Sill4:25 sccm (standard cubic centimeters per minute), At: 275 sccm, 10%PH3/N2:2 sccm, HF power: 15 W, pressure: 0.9 Torr and temperature: 350℃. In addition, for in thick fihn deposition on silicon substrate, a N20 and NH3 preprocessing method is proposed to suppress the formation of gas bubbles.展开更多
An improved method of fitting point-by-point is proposed to determine the absorption coefficient from infrared (IR) transmittance. With no necessity of empirical correction factors, the absorption coefficient can be...An improved method of fitting point-by-point is proposed to determine the absorption coefficient from infrared (IR) transmittance. With no necessity of empirical correction factors, the absorption coefficient can be accurately determined for the films with thin thicknesses. Based on this method, the structural properties of the hydrogenated amorphous silicon oxide materials (a-SiOx:H) are investigated. The oxygen-concentration-dependent variation of the Si-O-Si and the Si-H related modes in a-SiOx:H materials is discussed in detail.展开更多
Hydrogenated amorphous silicon nitride films(Si N x:H) are deposited at low temperature by high-frequency plasmaenhanced chemical vapor deposition(HF PECVD). The main effort is to investigate the roles of plasma ...Hydrogenated amorphous silicon nitride films(Si N x:H) are deposited at low temperature by high-frequency plasmaenhanced chemical vapor deposition(HF PECVD). The main effort is to investigate the roles of plasma frequency and plasma power density in determining the film properties particularly in stress. Information about chemical bonds in the films is obtained by Fourier transform infrared spectroscopy(FTIR). The stresses in the Si N x:H film are determined from substrate curvature measurements. It is shown that plasma frequency plays an important role in controlling the stresses in Si N x:H films. For silicon nitride layers grown at plasma frequency 40.68 MHz initial tensile stresses are observed to be in a range of 400 MPa-700 MPa. Measurements of the intrinsic stresses of silicon nitride films show that the stress quantity is sufficient for film applications in strained silicon photonics.展开更多
Amorphous silicon ( a-Si ) thin films were deposited on glass substrate by PECVD, and polycrystalline silicon ( poly- Si ) thin films were prepared by aluminum- induced crystallization ( AlC ). The effects of an...Amorphous silicon ( a-Si ) thin films were deposited on glass substrate by PECVD, and polycrystalline silicon ( poly- Si ) thin films were prepared by aluminum- induced crystallization ( AlC ). The effects of annealing temperature on the microstructure and morphology were investigated. The AlC poly-Si thin films were characterized by XRD, Raman and SEM. It is found that a-Si thin film has a amorphous structure after annealing at 400℃ for 20 min, a-Si films begin to crystallize after annealing at 450 ℃ for 20 min, and the crystallinity of a-Si thin films is enhanced obviously with the increment of annealing termperature.展开更多
During the last few decades, photothermal radiometry(PTR) has been greatly developed and widely applied in the field of nondestructive testing. However, the traditional PTR system employs an expensive lock-in amplif...During the last few decades, photothermal radiometry(PTR) has been greatly developed and widely applied in the field of nondestructive testing. However, the traditional PTR system employs an expensive lock-in amplifier to detect the weak photothermal signal, which leads to high cost and long test time. In this paper, a fast transmission PTR system based on sampling by using an internal computer sound card was developed to lower the system cost and shorter the test time. A piece of amorphous silicon(a:Si) thin film solar cells with artificial defects was prepared and tested by the system. The results show that the sharpened defects can be identified easily and quickly according to the significant peaks of the original infrared signal sampled by the internal computer sound card. Furthermore, more detailed defects can be investigated by processing the infrared signal. These validate the effectiveness of the proposed transmission PTR system as a low cost and efficient non-destructive test technique.展开更多
基金the National Natural Science Foundation of china(No.50372060)
文摘Hydrogenated amorphous silicon (a-Si: H) films were deposited on Si (100) and glass substrates by dielectric barrier discharge enhanced chemical vapour deposition (DBD-CVD) in (SiH4+H2) atmosphere at room temperature. Results of the thickness measurement, SEM (scanning electron microscope), Raman, and FTIR (Fourier transform infrared spectroscopy) show that with the increase in the applied peak voltage, the deposition rate and network order of the films increase, and the hydrogen bonding configurations mainly in di-hydrogen (Si-H2) and poly hydrogen (SiH2)n are introduced into the films. The UV-visible transmission spectra show that with the decrease in SiH4/ (SiHn+H2) the thin films' band gap shifts from 1.92 eV to 2.17 eV. These experimental results are in agreement with the theoretic analysis of the DBD discharge. The deposition of a-Si: H films by the DBD-CVD method as reported here for the first time is attractive because it allows fast deposition of a-Si: H films on large-area low-melting-point substrates and requires only a low cost of production without additional heating or pumping equipment.
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.
基金National Natural Science Foundation of China (Nos.60407013,60876081)the Shanghai-Applied Materials Research and Development Fund of China (No.06SA04)the National High Technology Research and Development Program of China (Nos.2009AA04Z317,2007AA04Z354-03)
文摘Influence of the parameters of plasma enhanced chemical vapor deposition (PECVD) on the surface morphology of hydrogenated amorphous silicon (α-Si:H) film was investigated. The root-mean-square (RMS) roughness of the film was measured by atomic force microscope (AFM) and the relevant results were analyzed using the surface smoothing mechanism of film deposition. It is shown that an α-Si:H film with smooth surface morphology can be obtained by increasing the PH3/N2 gas flow rate for 10% in a high frequency (HF) mode. For high power, however, the surface morphology of the film will deteriorate when the Sill4 gas flow rate increases. Furthermore, optimized parameters of PECVD for growing the film with smooth surface were obtained to be Sill4:25 sccm (standard cubic centimeters per minute), At: 275 sccm, 10%PH3/N2:2 sccm, HF power: 15 W, pressure: 0.9 Torr and temperature: 350℃. In addition, for in thick fihn deposition on silicon substrate, a N20 and NH3 preprocessing method is proposed to suppress the formation of gas bubbles.
基金supported by the National Basic Research Program of China(Grant Nos.2011CBA00705,2011CBA00706,and 2011CBA00707)the National Natural Science Foundation of China(Grant No.60976051)the Program for New Century Excellent Talents in University of China(Grant No.NCET-08-0295)
文摘An improved method of fitting point-by-point is proposed to determine the absorption coefficient from infrared (IR) transmittance. With no necessity of empirical correction factors, the absorption coefficient can be accurately determined for the films with thin thicknesses. Based on this method, the structural properties of the hydrogenated amorphous silicon oxide materials (a-SiOx:H) are investigated. The oxygen-concentration-dependent variation of the Si-O-Si and the Si-H related modes in a-SiOx:H materials is discussed in detail.
基金Project supported by RFBR(Grant No.14-03-91154 NNSF)the National Natural Science Foundation of China(Grant No.61411130212)
文摘Hydrogenated amorphous silicon nitride films(Si N x:H) are deposited at low temperature by high-frequency plasmaenhanced chemical vapor deposition(HF PECVD). The main effort is to investigate the roles of plasma frequency and plasma power density in determining the film properties particularly in stress. Information about chemical bonds in the films is obtained by Fourier transform infrared spectroscopy(FTIR). The stresses in the Si N x:H film are determined from substrate curvature measurements. It is shown that plasma frequency plays an important role in controlling the stresses in Si N x:H films. For silicon nitride layers grown at plasma frequency 40.68 MHz initial tensile stresses are observed to be in a range of 400 MPa-700 MPa. Measurements of the intrinsic stresses of silicon nitride films show that the stress quantity is sufficient for film applications in strained silicon photonics.
文摘Amorphous silicon ( a-Si ) thin films were deposited on glass substrate by PECVD, and polycrystalline silicon ( poly- Si ) thin films were prepared by aluminum- induced crystallization ( AlC ). The effects of annealing temperature on the microstructure and morphology were investigated. The AlC poly-Si thin films were characterized by XRD, Raman and SEM. It is found that a-Si thin film has a amorphous structure after annealing at 400℃ for 20 min, a-Si films begin to crystallize after annealing at 450 ℃ for 20 min, and the crystallinity of a-Si thin films is enhanced obviously with the increment of annealing termperature.
基金supported by the National Natural Science Foundation of China under Grant No.61379013the Excellent Doctoral Academic Support Program under Grant No.YBXSZC2013021
文摘During the last few decades, photothermal radiometry(PTR) has been greatly developed and widely applied in the field of nondestructive testing. However, the traditional PTR system employs an expensive lock-in amplifier to detect the weak photothermal signal, which leads to high cost and long test time. In this paper, a fast transmission PTR system based on sampling by using an internal computer sound card was developed to lower the system cost and shorter the test time. A piece of amorphous silicon(a:Si) thin film solar cells with artificial defects was prepared and tested by the system. The results show that the sharpened defects can be identified easily and quickly according to the significant peaks of the original infrared signal sampled by the internal computer sound card. Furthermore, more detailed defects can be investigated by processing the infrared signal. These validate the effectiveness of the proposed transmission PTR system as a low cost and efficient non-destructive test technique.