The nanocrystalline SiC films were prepared on Si then annealed at 800℃ and 1 000℃ for 30 minutes (111) substrates by rf magnetron sputtering and in a vacuum annealing system. The crystal structure and crystalliza...The nanocrystalline SiC films were prepared on Si then annealed at 800℃ and 1 000℃ for 30 minutes (111) substrates by rf magnetron sputtering and in a vacuum annealing system. The crystal structure and crystallization of as-annealed SiC films were determined by the Fourier transform infrared (FIR) absorption spectra and the X-ray diffraction (XRD) analysis. Measurement of photoluminescence (PL) of the nanocrystalline SiC (nc-SiC) films shows that the blue light with 473 nm and 477 nm wavelengths emitted at room temperature and that the PL peak shifts to shorter wavelength side and the PL intensity becomes stronger as the annealing temperature decreases. The time-resolved spectrum of the PL at 477 nm exhibits a bi-exponential decay process with lifetimes of 600 ps and 5 ns and a characteristic of the direct band gap. The strong blue light emission with short PL lifetimes suggests that the quantum confinement effect of the SiC nanocrystals resulted in the radiative recombination of the direct optical transitions.展开更多
Si-rich silicon oxide films were deposited by RF magnetron sputtering onto composite Si/SiO2 targets. After annealed at different temperature, the silicon oxide films embedded with silicon nanocrystals were obtained. ...Si-rich silicon oxide films were deposited by RF magnetron sputtering onto composite Si/SiO2 targets. After annealed at different temperature, the silicon oxide films embedded with silicon nanocrystals were obtained. The photoluminescenee(PL) from the silicon oxide films embedded with silicon nanocrystals was observed at room temperature. The strong peak is at 360 nm, its position is independent of the annealing temperature. The origin of the 360-nm PL in the silicon oxide films embedded with silicon nanoerystals was discussed.展开更多
A novel approach of two-step laser crystallization for the growth of poly-Si thin film on glass substrate is investigated. Using this approach, we fabricated poly-Si thin film transistors with electron mobility of 103...A novel approach of two-step laser crystallization for the growth of poly-Si thin film on glass substrate is investigated. Using this approach, we fabricated poly-Si thin film transistors with electron mobility of 103 cm2/V·s and on/off current ratio of 1×10~7.They are better than those of the poly-Si TFTs fabricated by conventional single-step excimer laser crystallization. We also analyzed the structure of the laser crystallized poly-Si thin film by spectroscopic ellipsometry, and proposed the models to simulate the poly-Si thin film and calculated the ellipsometric spectra. The calculated results are in good agreement with the measured results.展开更多
Highly conductive boron-doped hydrogenated microcrystalline silicon (μc-Si: H) films and solar cells are pre- pared by plasma enhanced chemical vapour deposition (PECVD). The effects of diborane concentration, t...Highly conductive boron-doped hydrogenated microcrystalline silicon (μc-Si: H) films and solar cells are pre- pared by plasma enhanced chemical vapour deposition (PECVD). The effects of diborane concentration, thickness and substrate temperature on the growth and properties of B-doped layers and the performance of solar cells with high deposited rate i-layers are investigated. With the optimum p-layer deposition parameters, a higher efficiency of 5.5% is obtained with 0.78nm/s deposited i-layers. In addition, the carriers transport mechanism of p-type μc-Si: H films is discussed.展开更多
Hydrogen bonding configurations and hydrogen content in hydrogenated amorphous silicon (a-Si:H) thin films prepared at different precursor gas temperatures with undiluted silane have been investigated by means of Four...Hydrogen bonding configurations and hydrogen content in hydrogenated amorphous silicon (a-Si:H) thin films prepared at different precursor gas temperatures with undiluted silane have been investigated by means of Fourier transform infrared (FTIR) spectroscopy.The results show that the gas temperature before precursor gases entering the glow-discharge zone re-markably influences the hydrogen bonding configurations and the hydrogen content in a-Si:H thin films.The hydrogen content decreases from 18% down to 11% when increasing the gas temperature from room temperature (RT) to 433 K.Meanwhile,the clustered hydrogen at the physical film surface or at the internal surfaces of the microvoids decreases,indicating that a-Si:H thin films are densified at higher precursor gas temperatures.For a-Si:H thin films deposited at gas temperature of 433 K,the isolated silicon-hydrogen bonding configuration is predominant in the testing films.展开更多
Because crystalline silicon thin film (CSiTF) solar cells possess the advantages of crystalline silicon solar cells such as high ef- ficiency and stable performance and those of thin film solar cells such as low cos...Because crystalline silicon thin film (CSiTF) solar cells possess the advantages of crystalline silicon solar cells such as high ef- ficiency and stable performance and those of thin film solar cells such as low cost and so on, it is regarded as the next genera- tion solar cell technology, which is most likely to replace the existing crystalline silicon solar cell technology. In this paper, we performed device simulation on the epitaxial CSiTF solar cell by using PCI D software. In order to make simulation results closer to the actual situation, we adopted a more realistic device structure and parameters. On this basis, we comprehensively and systematically investigated the effect of physical parameters of back surface field (BSF) layer, base and emitter, electrical quality of crystalline silicon active layer, situation of surface passivation, internal recombination and p-n junction leakage on the optoelectronic performance of the epitaxial CSiTF solar cell. Among various factors affecting the efficiency of the epitaxial CSiTF solar cell, we identified the three largest efficiency-affecting parameters. They are the base minority carrier diffusion length, the diode dark saturation current and the front surface recombination velocity in order. Through simulations, we found that the base is not the thicker the better, and the base minority carrier diffusion length must be taken into account when deter- mining the optimal base thickness. When the base minority carrier diffusion length is smaller, the optimal base thickness should be less than or equal to the base minority carrier diffusion length; when the base minority carrier diffusion length is larger, the base minority carrier diffusion length should be at least twice the optimal base thickness. In addition, this paper not only illustrates the simulation results but also explains their changes from the aspect of physical mechanisms. Because epitaxi- al CSiTF solar cells possess a device structure that is similar to crystalline silicon solar cells, the conclusions drawn in this pa- per are also applied to crystalline silicon solar cells to a certain extent, particularly to thin silicon solar cells which are the hot- test research topic at present.展开更多
The relationship between structure and electronic properties of phosphorus-doped hydrogenated amorphous silicon(a-Si:H) thin films was investigated.Samples with different features were prepared by plasma enhanced chem...The relationship between structure and electronic properties of phosphorus-doped hydrogenated amorphous silicon(a-Si:H) thin films was investigated.Samples with different features were prepared by plasma enhanced chemical vapor deposition(PECVD) at various substrate temperatures.Raman spectroscopy and Fourier transform infrared(FTIR) spectroscopy were used to evaluate the structural evolution,meanwhile,electronic-spin resonance(ESR) and optical measurement were applied to explore the electronic properties of P-doped a-Si:H thin films.The results revealed that the changes in materials structure affect directly the electronic properties and the doping efficiency of dopant.展开更多
基金The project supported by the National Natural Science Founda-tion of China(Grant No.60476003)
文摘The nanocrystalline SiC films were prepared on Si then annealed at 800℃ and 1 000℃ for 30 minutes (111) substrates by rf magnetron sputtering and in a vacuum annealing system. The crystal structure and crystallization of as-annealed SiC films were determined by the Fourier transform infrared (FIR) absorption spectra and the X-ray diffraction (XRD) analysis. Measurement of photoluminescence (PL) of the nanocrystalline SiC (nc-SiC) films shows that the blue light with 473 nm and 477 nm wavelengths emitted at room temperature and that the PL peak shifts to shorter wavelength side and the PL intensity becomes stronger as the annealing temperature decreases. The time-resolved spectrum of the PL at 477 nm exhibits a bi-exponential decay process with lifetimes of 600 ps and 5 ns and a characteristic of the direct band gap. The strong blue light emission with short PL lifetimes suggests that the quantum confinement effect of the SiC nanocrystals resulted in the radiative recombination of the direct optical transitions.
基金National Natural Science Foundation of China(60336010)
文摘Si-rich silicon oxide films were deposited by RF magnetron sputtering onto composite Si/SiO2 targets. After annealed at different temperature, the silicon oxide films embedded with silicon nanocrystals were obtained. The photoluminescenee(PL) from the silicon oxide films embedded with silicon nanocrystals was observed at room temperature. The strong peak is at 360 nm, its position is independent of the annealing temperature. The origin of the 360-nm PL in the silicon oxide films embedded with silicon nanoerystals was discussed.
文摘A novel approach of two-step laser crystallization for the growth of poly-Si thin film on glass substrate is investigated. Using this approach, we fabricated poly-Si thin film transistors with electron mobility of 103 cm2/V·s and on/off current ratio of 1×10~7.They are better than those of the poly-Si TFTs fabricated by conventional single-step excimer laser crystallization. We also analyzed the structure of the laser crystallized poly-Si thin film by spectroscopic ellipsometry, and proposed the models to simulate the poly-Si thin film and calculated the ellipsometric spectra. The calculated results are in good agreement with the measured results.
基金the State Key Development Program for Basic Research of China(No.2006CB202601)the Basic Research Project of Henan Province(No.072300410140)~~
文摘Highly conductive boron-doped hydrogenated microcrystalline silicon (μc-Si: H) films and solar cells are pre- pared by plasma enhanced chemical vapour deposition (PECVD). The effects of diborane concentration, thickness and substrate temperature on the growth and properties of B-doped layers and the performance of solar cells with high deposited rate i-layers are investigated. With the optimum p-layer deposition parameters, a higher efficiency of 5.5% is obtained with 0.78nm/s deposited i-layers. In addition, the carriers transport mechanism of p-type μc-Si: H films is discussed.
基金supported by the Ministry of Education of People’s Republic of China (Grant No. J2009JBPY003)
文摘Hydrogen bonding configurations and hydrogen content in hydrogenated amorphous silicon (a-Si:H) thin films prepared at different precursor gas temperatures with undiluted silane have been investigated by means of Fourier transform infrared (FTIR) spectroscopy.The results show that the gas temperature before precursor gases entering the glow-discharge zone re-markably influences the hydrogen bonding configurations and the hydrogen content in a-Si:H thin films.The hydrogen content decreases from 18% down to 11% when increasing the gas temperature from room temperature (RT) to 433 K.Meanwhile,the clustered hydrogen at the physical film surface or at the internal surfaces of the microvoids decreases,indicating that a-Si:H thin films are densified at higher precursor gas temperatures.For a-Si:H thin films deposited at gas temperature of 433 K,the isolated silicon-hydrogen bonding configuration is predominant in the testing films.
基金supported by the National Natural Science Foundation of China (Grant No. 50802118)Science & Technology Research Project of Guangdong Province (Grant Nos. 2011A032304001,2010B090400020)the Fundamental Research Funds for the Central Universities (Grant No. 2011300003161469)
文摘Because crystalline silicon thin film (CSiTF) solar cells possess the advantages of crystalline silicon solar cells such as high ef- ficiency and stable performance and those of thin film solar cells such as low cost and so on, it is regarded as the next genera- tion solar cell technology, which is most likely to replace the existing crystalline silicon solar cell technology. In this paper, we performed device simulation on the epitaxial CSiTF solar cell by using PCI D software. In order to make simulation results closer to the actual situation, we adopted a more realistic device structure and parameters. On this basis, we comprehensively and systematically investigated the effect of physical parameters of back surface field (BSF) layer, base and emitter, electrical quality of crystalline silicon active layer, situation of surface passivation, internal recombination and p-n junction leakage on the optoelectronic performance of the epitaxial CSiTF solar cell. Among various factors affecting the efficiency of the epitaxial CSiTF solar cell, we identified the three largest efficiency-affecting parameters. They are the base minority carrier diffusion length, the diode dark saturation current and the front surface recombination velocity in order. Through simulations, we found that the base is not the thicker the better, and the base minority carrier diffusion length must be taken into account when deter- mining the optimal base thickness. When the base minority carrier diffusion length is smaller, the optimal base thickness should be less than or equal to the base minority carrier diffusion length; when the base minority carrier diffusion length is larger, the base minority carrier diffusion length should be at least twice the optimal base thickness. In addition, this paper not only illustrates the simulation results but also explains their changes from the aspect of physical mechanisms. Because epitaxi- al CSiTF solar cells possess a device structure that is similar to crystalline silicon solar cells, the conclusions drawn in this pa- per are also applied to crystalline silicon solar cells to a certain extent, particularly to thin silicon solar cells which are the hot- test research topic at present.
基金supported by the Fundamental Research Funds for the Central Universities
文摘The relationship between structure and electronic properties of phosphorus-doped hydrogenated amorphous silicon(a-Si:H) thin films was investigated.Samples with different features were prepared by plasma enhanced chemical vapor deposition(PECVD) at various substrate temperatures.Raman spectroscopy and Fourier transform infrared(FTIR) spectroscopy were used to evaluate the structural evolution,meanwhile,electronic-spin resonance(ESR) and optical measurement were applied to explore the electronic properties of P-doped a-Si:H thin films.The results revealed that the changes in materials structure affect directly the electronic properties and the doping efficiency of dopant.