Relationshipabout The Size And Fluctuation Of Pyramid On The Single Crystal Si Surface And Minority Carrier Lifetime

High-efficiency crystalline silicon solar cell is one of the hottestresearch in the photovoltaic field. Effectively regulate the size of thesilicon surface pyramid is a key technology in solar energy research.Minority carrier lifetime is very important in the physical parametersreflecting the performance of the semiconductor materials and devices.Measuring the minority carrier life time is one of the main methods toevaluate the function of raw materials and device technology. There are alarge number of dangling bonds, broken bonds as well as unsaturatedbonds semiconductor silicon surface, easily formed the recombinationcenter in the band gap, increasing the composite of carrier on the surface,and seriously decrease the minority carrier life time. It is evident that theminority carrier lifetime is very important for device, and the conclusion isobvious. Long minority carrier lifetime can be made of high-performancebatteries, on the contrary, the cell conversion efficiency will be greatlyreduced. Non-equilibrium carrier recombination is a key factor indetermining the minority carrier lifetime. The minority carrier lifetime andconversion efficiency strongly depend on the size and distribution ofpyramid on the single crystal Si. The surface of single crystal Si had beentextured in different alkaline solution. We had observed the surfacemicro-structure using SEM, and measured the minority carrier lifetime and conversion efficiency for the corresponding samples. The experimentalresults illustrate that the surface micro-structure is different for the sampleetched in different alkaline solution. It was also observed that the largesize-pyramid and large fluctuation in pyramid size could reduce theminority carrier lifetime of single crystal Si, which leads to the lowconversion efficiency of solar cell. In contrary, for the solar cell with thesurface full of small size and small fluctuation in size of pyramid, theminority carrier lifetime and the conversion efficiency is comparativelyhigh.