The effect of oxygen precipitates on minority carrier lifetime and performance of solar cell was studied by means of Fourier Transform Infrared Spectroscopy (FTIR), quasi-steady state photoconductance (QSSPCD), optica...The effect of oxygen precipitates on minority carrier lifetime and performance of solar cell was studied by means of Fourier Transform Infrared Spectroscopy (FTIR), quasi-steady state photoconductance (QSSPCD), optical microscope, spectrum response and solar cell efficiency test. The minority carrier lifetime and performance of solar cell reduced depend on oxygen precipitates. A few of oxygen precipitates have formed after single-step annealing; and they do not impact the efficiency dramatically. Pre-annealing at 650 ℃ for 4 h enhances the oxygen precipitation when it is subjected to middle temperature annealing. The solar cells performance decayed sharply. Especially annealing at 950 ℃ for 3 h, the Vos and Isc of cells decrease 12% and 25% respectively. Few oxygen precipitates have formed in silicon after high temperature annealing at about 1050 ℃ whether pre-annealing is used or not, and the performance of cells is not be affected.展开更多
The effects of the transition metals copper and nickel on oxygen precipitation in Czochralski silicon under a rapid thermal process are investigated. It is found that interstitial copper has almost no effect on oxygen...The effects of the transition metals copper and nickel on oxygen precipitation in Czochralski silicon under a rapid thermal process are investigated. It is found that interstitial copper has almost no effect on oxygen precipitation,but copper precipitation markedly enhances oxygen precipitation. However, neither interstitial nickel nor nickel precipitation affects oxygen precipitation. The reasons for the effects of copper and nickel contamination on oxygen precipitation are discussed in light of oxygen precipitation nucleation theory.展开更多
Annealing effect of the oxygen precipitation and the induced defects have been investigated on the fast neutron irradiated Czochralski silicon (CZ-Si) by infrared absorption spectrum and the optical microscopy. It i...Annealing effect of the oxygen precipitation and the induced defects have been investigated on the fast neutron irradiated Czochralski silicon (CZ-Si) by infrared absorption spectrum and the optical microscopy. It is found that the fast neutron irradiation greatly accelerates the oxygen precipitation that leads to a sharp decrease of the interstitial oxygen with the annealing time. At room temperature (RT), the 1107cm^-1 infrared absorption band of interstitial oxygen becomes weak and broadens to low energy side. At low temperature, the infrared absorption peaks appear at 1078cm^-1, 1096cm^-1, and 1182cm^-1, related to different shapes of the oxygen precipitates. The bulk microdefects, including stacking faults, dislocations and dislocation loops, were observed by the optical microscopy. New or large stacking faults grow up when the silicon self-interstitial atoms are created and aggregate with oxygen precipitation.展开更多
By means of low-temperature (10 K) Fourier transform infrared absorption spectroscopy, the kinetics of nitrogen indiffusion in Czochralski (CZ) silicon annealed at 1150-1250℃ in nitrogen ambient is investigated. ...By means of low-temperature (10 K) Fourier transform infrared absorption spectroscopy, the kinetics of nitrogen indiffusion in Czochralski (CZ) silicon annealed at 1150-1250℃ in nitrogen ambient is investigated. Moreover, the nitrogen diffusivities in CZ silicon at elevated temperatures deduced herein are in good agreement with those previously obtained in float-zone silicon, thus leading to the conclusion that the nitrogen indiffusion in CZ silicon at elevated temperatures is via nitrogen pairs.展开更多
Fast-neutron irradiated nitrogen-doped Czochralski silicon(NCZ-Si)was annealed at 1100℃for different time,then FTIR and optical microscope were used to study the behavior of oxygen.It is found that[Oi]increase at the...Fast-neutron irradiated nitrogen-doped Czochralski silicon(NCZ-Si)was annealed at 1100℃for different time,then FTIR and optical microscope were used to study the behavior of oxygen.It is found that[Oi]increase at the early stage then decrease along with the increasing of anneal time.High density induced-defects can be found in the cleavage plane.By comparing NCZ-Si with Czochralski silicon(CZ-Si),[Oi]in NCZ-Si decrease more after anneal 24 h.展开更多
We characterized strip-like shadows in cast multicrystalline silicon(mc-Si) ingots. Blocks and wafers were analyzed using scanning infrared microscopy, photoluminescence spectroscopy, laser scanning confocal microscop...We characterized strip-like shadows in cast multicrystalline silicon(mc-Si) ingots. Blocks and wafers were analyzed using scanning infrared microscopy, photoluminescence spectroscopy, laser scanning confocal microscopy, field-emission scanning electron microscopy, X-ray energy-dispersive spectrometry, and microwave photoconductivity decay technique. The effect on solar cell performance is discussed. The results show that the non-microcrystalline shadow region in Si ingots consists of precipitates of Fe, O, and C. The size of these Fe–O–C precipitates found at the shadow region is25 μm. Fe–O–C impurities can slightly reduce the minority carrier lifetime of the wafers while severely decrease in shunt resistance, leading to the increase in reverse current of the solar cells and degradation in cell efficiency.展开更多
基金This project was financially supported by the National Natural Science Foundation of China (No.50572022).
文摘The effect of oxygen precipitates on minority carrier lifetime and performance of solar cell was studied by means of Fourier Transform Infrared Spectroscopy (FTIR), quasi-steady state photoconductance (QSSPCD), optical microscope, spectrum response and solar cell efficiency test. The minority carrier lifetime and performance of solar cell reduced depend on oxygen precipitates. A few of oxygen precipitates have formed after single-step annealing; and they do not impact the efficiency dramatically. Pre-annealing at 650 ℃ for 4 h enhances the oxygen precipitation when it is subjected to middle temperature annealing. The solar cells performance decayed sharply. Especially annealing at 950 ℃ for 3 h, the Vos and Isc of cells decrease 12% and 25% respectively. Few oxygen precipitates have formed in silicon after high temperature annealing at about 1050 ℃ whether pre-annealing is used or not, and the performance of cells is not be affected.
文摘The effects of the transition metals copper and nickel on oxygen precipitation in Czochralski silicon under a rapid thermal process are investigated. It is found that interstitial copper has almost no effect on oxygen precipitation,but copper precipitation markedly enhances oxygen precipitation. However, neither interstitial nickel nor nickel precipitation affects oxygen precipitation. The reasons for the effects of copper and nickel contamination on oxygen precipitation are discussed in light of oxygen precipitation nucleation theory.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 50032010 and 50472034) and the Natural Science Foundation of Hebei Province, China (Grant Nos 601047 and E2005000048).
文摘Annealing effect of the oxygen precipitation and the induced defects have been investigated on the fast neutron irradiated Czochralski silicon (CZ-Si) by infrared absorption spectrum and the optical microscopy. It is found that the fast neutron irradiation greatly accelerates the oxygen precipitation that leads to a sharp decrease of the interstitial oxygen with the annealing time. At room temperature (RT), the 1107cm^-1 infrared absorption band of interstitial oxygen becomes weak and broadens to low energy side. At low temperature, the infrared absorption peaks appear at 1078cm^-1, 1096cm^-1, and 1182cm^-1, related to different shapes of the oxygen precipitates. The bulk microdefects, including stacking faults, dislocations and dislocation loops, were observed by the optical microscopy. New or large stacking faults grow up when the silicon self-interstitial atoms are created and aggregate with oxygen precipitation.
基金the National Natural Science Foundation of China under Grant No 50672085, the Programme for Changjiang and Innovative Research Team of China under Grant No 0651, and the Programme for New Century Excellent Talents in University under Grant No 040537. The author is grateful Dr J. Vonhellmont at the University of Gent, Belgium for helpful discussion.
文摘By means of low-temperature (10 K) Fourier transform infrared absorption spectroscopy, the kinetics of nitrogen indiffusion in Czochralski (CZ) silicon annealed at 1150-1250℃ in nitrogen ambient is investigated. Moreover, the nitrogen diffusivities in CZ silicon at elevated temperatures deduced herein are in good agreement with those previously obtained in float-zone silicon, thus leading to the conclusion that the nitrogen indiffusion in CZ silicon at elevated temperatures is via nitrogen pairs.
基金Project supported by the National Nature Science Foundation of China(50472034)the Natural Science Foundation of Hebei Province(E2005000048)Education Ministry Doctoral Program Foundation of China(20050080006)
文摘Fast-neutron irradiated nitrogen-doped Czochralski silicon(NCZ-Si)was annealed at 1100℃for different time,then FTIR and optical microscope were used to study the behavior of oxygen.It is found that[Oi]increase at the early stage then decrease along with the increasing of anneal time.High density induced-defects can be found in the cleavage plane.By comparing NCZ-Si with Czochralski silicon(CZ-Si),[Oi]in NCZ-Si decrease more after anneal 24 h.
基金supported by the National Natural Science Foundation of China(No.51532007)the Fundamental Research Funds for the Central Universities
文摘We characterized strip-like shadows in cast multicrystalline silicon(mc-Si) ingots. Blocks and wafers were analyzed using scanning infrared microscopy, photoluminescence spectroscopy, laser scanning confocal microscopy, field-emission scanning electron microscopy, X-ray energy-dispersive spectrometry, and microwave photoconductivity decay technique. The effect on solar cell performance is discussed. The results show that the non-microcrystalline shadow region in Si ingots consists of precipitates of Fe, O, and C. The size of these Fe–O–C precipitates found at the shadow region is25 μm. Fe–O–C impurities can slightly reduce the minority carrier lifetime of the wafers while severely decrease in shunt resistance, leading to the increase in reverse current of the solar cells and degradation in cell efficiency.