To find out the causation of inhomogeneous minority carrier lifetime distribution in high quality multicrystalline silicon （mc-Si） wafers, impurities and lattice defects were systematically studied by means of Fouri...To find out the causation of inhomogeneous minority carrier lifetime distribution in high quality multicrystalline silicon （mc-Si） wafers, impurities and lattice defects were systematically studied by means of Fourier transform infrared （FTIR） spectroscopy and metallography, Inhomogeneously distributed oxygen impurity and dislocations were demonstrated to be key leading factors, and the restriction mechanism was discussed. Scattering process caused by ionized impurities and dislocations decreased carrier mobility, while carrier concentration was not significantly affected. Measurements showed that resistivity was higher and more dispersive in low lifetime area. Solar cells were fabricated with these wafers. Cells＇ efficiency of inhomogeneous ones exhibited averagely 0.27% lower than the regular ones in absolute terms. Recombination centers and leakage loss induced by dislocations and impurities led to the reduction in shunt resistors and open-circuit voltage, and then affected the performance of cells.展开更多
The investigation of multi-crystalline silicon （mc-Si） surface etching technology is a key point in solar cell research. In this paper, mc-Si surface was etched in the common alkaline solution modified by an additiv...The investigation of multi-crystalline silicon （mc-Si） surface etching technology is a key point in solar cell research. In this paper, mc-Si surface was etched in the common alkaline solution modified by an additive for 20 minutes at 78-80~C. Samples＇ surface morphology was observed by scanning electron microscope （SEM）. It is firstly found that the etched mc-Si surface has the uniform distribution of trap pits although the morphologies of trap pits are slightly different on different crystallographic planes. Si （100） plane was covered with many small Si-mountaln ranges or long V-shape channels arranged in a crisscross pat- tern. For （110） plane and （111） plane, they were full of a lot of triangle pit-traps （or quadrilateral holes） and twisted earthworm trap pits, respectively. The measured reflectance of the sample was 20.5% at wavelength range of 400--900 nm. These results illustrate that alkaline solution modified by an additive can effectively etch out trap pits with a good trapping light effect on mc-Si surfaces. This method should be very valuable for mc-Si solar cells.展开更多
基金financially supported by the Department of Education of Guangdong Province(Grant No.2013CXZDA002)Guangzhou Science and Technology Department(Grant No.2014Y2-00221)
文摘To find out the causation of inhomogeneous minority carrier lifetime distribution in high quality multicrystalline silicon （mc-Si） wafers, impurities and lattice defects were systematically studied by means of Fourier transform infrared （FTIR） spectroscopy and metallography, Inhomogeneously distributed oxygen impurity and dislocations were demonstrated to be key leading factors, and the restriction mechanism was discussed. Scattering process caused by ionized impurities and dislocations decreased carrier mobility, while carrier concentration was not significantly affected. Measurements showed that resistivity was higher and more dispersive in low lifetime area. Solar cells were fabricated with these wafers. Cells＇ efficiency of inhomogeneous ones exhibited averagely 0.27% lower than the regular ones in absolute terms. Recombination centers and leakage loss induced by dislocations and impurities led to the reduction in shunt resistors and open-circuit voltage, and then affected the performance of cells.
基金supported by the Shanghai Aerospace Foundation (Grant No. GC072003)
文摘The investigation of multi-crystalline silicon （mc-Si） surface etching technology is a key point in solar cell research. In this paper, mc-Si surface was etched in the common alkaline solution modified by an additive for 20 minutes at 78-80~C. Samples＇ surface morphology was observed by scanning electron microscope （SEM）. It is firstly found that the etched mc-Si surface has the uniform distribution of trap pits although the morphologies of trap pits are slightly different on different crystallographic planes. Si （100） plane was covered with many small Si-mountaln ranges or long V-shape channels arranged in a crisscross pat- tern. For （110） plane and （111） plane, they were full of a lot of triangle pit-traps （or quadrilateral holes） and twisted earthworm trap pits, respectively. The measured reflectance of the sample was 20.5% at wavelength range of 400--900 nm. These results illustrate that alkaline solution modified by an additive can effectively etch out trap pits with a good trapping light effect on mc-Si surfaces. This method should be very valuable for mc-Si solar cells.
