Studies of nanoindentation were performed on nc-Si：H films to evaluate the effects of the fabrication processes on their mechanical properties. It is observed that with the decrease of the SiH4 contents, the grain si...Studies of nanoindentation were performed on nc-Si：H films to evaluate the effects of the fabrication processes on their mechanical properties. It is observed that with the decrease of the SiH4 contents, the grain size of the films increases gradually, and as does the crystalline volume fraction. The smaller the grains become, the more homogeneous the films, and the more even the hardness as well as the modulus will be. The hardness and the modulus will increase with the substrate＇s temperature rising. The hardness and the modulus of the nc-Si：H films on the Si substrate prove to be higher than those on the glass substrate given the same technology parameters. How- ever, the films on the glass substrate appear to be more homogeneous.展开更多
The AC impedance of amorphous-nano-crystalline silicon composite thin films (a-nc-Si:H) from mHz to MHz at different temperatures has been studied. The samples were prepared by Plasma Enhanced Chemical Vapor Depositio...The AC impedance of amorphous-nano-crystalline silicon composite thin films (a-nc-Si:H) from mHz to MHz at different temperatures has been studied. The samples were prepared by Plasma Enhanced Chemical Vapor Deposition technique. The X-ray diffraction and high resolution electron microscopy showed that films consist of isolated nano-crystals embedded in amorphous matrix. In analysis of impedance data, two approaches were tested: the ideal Deby type equivalent circuit and modified one, with CPE (constant phase elements). It was found that the later better fits to results. The amorphous matrix showed larger resistance and lower capacity than nano-crystals. By heat treatment in vacuum, the capacity for both phases changes, according to expected change in size of ordered domains.展开更多
The magnetic field profiles,which are produced by three ways in the deposition chamber and plasma chamber of single coil divergent field MWECR CVD system,are investigated.The magnetic field gradient of these magnetic ...The magnetic field profiles,which are produced by three ways in the deposition chamber and plasma chamber of single coil divergent field MWECR CVD system,are investigated.The magnetic field gradient of these magnetic field profiles is obtained quantitatively by using Lorentz fit.The results indicate that the gradient value of the magnetic field profile near by the substrate,which is produced by a coil current with 137.7A if a SmCo permanent magnet is equipped under the substrate holder,is the largest;when the SmCo permanent magnet is taken away,the larger one is produced by the coil current with 137.7A and the smallest one produced by a coil current with 115.2A.High deposition rate of a-Si∶H film is observed near by the substrate with high magnetic field gradient.But uneven deposition rate along the radius of the sample holder is also found by infrared analysis technology when sample is deposited in magnetic field profile,which is produced by the coil current with 137.7A if the SmCo permanent magnet is equipped under the substrate holder.展开更多
Using H 2 diluted silane,series of μc Si∶H films are fabricated at low temperature with VHF PECVD.The thickness measurements reveal that the deposition rates are obviously enhanced with higher plasma excitation ...Using H 2 diluted silane,series of μc Si∶H films are fabricated at low temperature with VHF PECVD.The thickness measurements reveal that the deposition rates are obviously enhanced with higher plasma excitation frequency or working pressure,but increase firstly and then decrease with the increase of plasma power density.Raman spectra show that the crystallinity and the average grain sizes of the films strongly depend on the temperature of substrate and the concentration of silane.However,the plasma excitation frequency only has effect on the crystallinity,and a maximum occurs during the further increase of plasma excitation frequency.From XRD and TEM experiments,three preferential crystalline orientations (111),(220) and (311) are observed,and the average grain sizes are different for every crystalline orientation.展开更多
Hydrogenated silicon nitride films as an effective antireflection and passivation coating of silicon solar cell were prepared on p-type polished silicon substrate （1.0 f^em） by direct LF-PECVD （low frequency plasma...Hydrogenated silicon nitride films as an effective antireflection and passivation coating of silicon solar cell were prepared on p-type polished silicon substrate （1.0 f^em） by direct LF-PECVD （low frequency plasma enhanced chemical vapor deposition） of Centrotherm. The preferable passivation effect was obtained and the refractive index was in the range of 2.017-2.082. The refractive index of the hydrogenated silicon nitride films became larger with the increase of the pressure. Fourier transform infrared spectroscopy was used to study the pressure influence on the film structural properties. The results highlighted high hydrogen bond and high Si-N bonds density in the film, which were greatly influenced by the pressure. The passivation effect of the films was infuenced by the Si dangling bonds density. Finally the effective minority liftetime degradation with time was shown and discussed by considering the relationship between the structural properties and passivation.展开更多
采用常规射频等离子体增强化学气相沉积方法,以高氢稀释的Si H4为源气体和以PH3为掺杂剂,制备了磷掺杂的氢化纳米晶硅薄膜。结果表明,薄膜的生长速率随PH3/Si H4流量比（Cp）增加而显著减小。Raman谱的研究证实,随Cp增加,薄膜的晶化率...采用常规射频等离子体增强化学气相沉积方法,以高氢稀释的Si H4为源气体和以PH3为掺杂剂,制备了磷掺杂的氢化纳米晶硅薄膜。结果表明,薄膜的生长速率随PH3/Si H4流量比（Cp）增加而显著减小。Raman谱的研究证实,随Cp增加,薄膜的晶化率经历了先增大后减小的过程,当Cp=1.0%,晶化率达到最大值45.9%。傅里叶变换红外吸收谱测量结果显示,薄膜中的H含量在Cp=2.0%时达到最低值9.5%。光学测量结果表明,本征和掺P的氢化纳米晶硅薄膜在可见光谱范围呈现出良好的光吸收特性,在0.8~3.0 e V范围内,nc-Si（P）∶H薄膜的吸收系数显著大于c-Si。和α-Si∶H薄膜相比,虽然短波范围的吸收系数较低,但是在hν〈1.7 e V区域,nc-Si（P）∶H薄膜的吸收系数要高两到三个量级,显示出优良的红光响应。电学测量表明,适当掺P会显著提高氢化纳米晶硅薄膜的暗电导率,当Cp=0.5%时,薄膜的暗电导率可达5.4 S·cm-1。展开更多
基金National Natural Science Foundation of China (Grants 10432050 and 90305026)
文摘Studies of nanoindentation were performed on nc-Si：H films to evaluate the effects of the fabrication processes on their mechanical properties. It is observed that with the decrease of the SiH4 contents, the grain size of the films increases gradually, and as does the crystalline volume fraction. The smaller the grains become, the more homogeneous the films, and the more even the hardness as well as the modulus will be. The hardness and the modulus will increase with the substrate＇s temperature rising. The hardness and the modulus of the nc-Si：H films on the Si substrate prove to be higher than those on the glass substrate given the same technology parameters. How- ever, the films on the glass substrate appear to be more homogeneous.
文摘The AC impedance of amorphous-nano-crystalline silicon composite thin films (a-nc-Si:H) from mHz to MHz at different temperatures has been studied. The samples were prepared by Plasma Enhanced Chemical Vapor Deposition technique. The X-ray diffraction and high resolution electron microscopy showed that films consist of isolated nano-crystals embedded in amorphous matrix. In analysis of impedance data, two approaches were tested: the ideal Deby type equivalent circuit and modified one, with CPE (constant phase elements). It was found that the later better fits to results. The amorphous matrix showed larger resistance and lower capacity than nano-crystals. By heat treatment in vacuum, the capacity for both phases changes, according to expected change in size of ordered domains.
文摘The magnetic field profiles,which are produced by three ways in the deposition chamber and plasma chamber of single coil divergent field MWECR CVD system,are investigated.The magnetic field gradient of these magnetic field profiles is obtained quantitatively by using Lorentz fit.The results indicate that the gradient value of the magnetic field profile near by the substrate,which is produced by a coil current with 137.7A if a SmCo permanent magnet is equipped under the substrate holder,is the largest;when the SmCo permanent magnet is taken away,the larger one is produced by the coil current with 137.7A and the smallest one produced by a coil current with 115.2A.High deposition rate of a-Si∶H film is observed near by the substrate with high magnetic field gradient.But uneven deposition rate along the radius of the sample holder is also found by infrared analysis technology when sample is deposited in magnetic field profile,which is produced by the coil current with 137.7A if the SmCo permanent magnet is equipped under the substrate holder.
文摘Using H 2 diluted silane,series of μc Si∶H films are fabricated at low temperature with VHF PECVD.The thickness measurements reveal that the deposition rates are obviously enhanced with higher plasma excitation frequency or working pressure,but increase firstly and then decrease with the increase of plasma power density.Raman spectra show that the crystallinity and the average grain sizes of the films strongly depend on the temperature of substrate and the concentration of silane.However,the plasma excitation frequency only has effect on the crystallinity,and a maximum occurs during the further increase of plasma excitation frequency.From XRD and TEM experiments,three preferential crystalline orientations (111),(220) and (311) are observed,and the average grain sizes are different for every crystalline orientation.
文摘Hydrogenated silicon nitride films as an effective antireflection and passivation coating of silicon solar cell were prepared on p-type polished silicon substrate （1.0 f^em） by direct LF-PECVD （low frequency plasma enhanced chemical vapor deposition） of Centrotherm. The preferable passivation effect was obtained and the refractive index was in the range of 2.017-2.082. The refractive index of the hydrogenated silicon nitride films became larger with the increase of the pressure. Fourier transform infrared spectroscopy was used to study the pressure influence on the film structural properties. The results highlighted high hydrogen bond and high Si-N bonds density in the film, which were greatly influenced by the pressure. The passivation effect of the films was infuenced by the Si dangling bonds density. Finally the effective minority liftetime degradation with time was shown and discussed by considering the relationship between the structural properties and passivation.
文摘采用常规射频等离子体增强化学气相沉积方法,以高氢稀释的Si H4为源气体和以PH3为掺杂剂,制备了磷掺杂的氢化纳米晶硅薄膜。结果表明,薄膜的生长速率随PH3/Si H4流量比（Cp）增加而显著减小。Raman谱的研究证实,随Cp增加,薄膜的晶化率经历了先增大后减小的过程,当Cp=1.0%,晶化率达到最大值45.9%。傅里叶变换红外吸收谱测量结果显示,薄膜中的H含量在Cp=2.0%时达到最低值9.5%。光学测量结果表明,本征和掺P的氢化纳米晶硅薄膜在可见光谱范围呈现出良好的光吸收特性,在0.8~3.0 e V范围内,nc-Si（P）∶H薄膜的吸收系数显著大于c-Si。和α-Si∶H薄膜相比,虽然短波范围的吸收系数较低,但是在hν〈1.7 e V区域,nc-Si（P）∶H薄膜的吸收系数要高两到三个量级,显示出优良的红光响应。电学测量表明,适当掺P会显著提高氢化纳米晶硅薄膜的暗电导率,当Cp=0.5%时,薄膜的暗电导率可达5.4 S·cm-1。
