多晶铸锭技术（英文版）.pdf

Technology Advancement in.Silicon Crystal Materials for Solar CellsL/GHT OLJR FUTUREYuepeng Wan,Dr.-Ing.CTO,LDK Solar Co.LTD.07/22/2009,ShanghaiPV production chain for c-Si cells冶金硅料Metallurgical silicon高纯硅料pure silicon raw materialLDK硅矿石Silicon ore硅锭IngotI-BEST Solar电池组件 module电池发电系统solar systemfa MB2C-Si solar cells keep market domination Continued price drop of polysilicon.Emerging alternative low-cost silicon feedstock,eg,UMG.Benefit from the similarity of manufacturing processes with semiconductor.Continuous manufacturing technology development keeps the cost down.Disruptive technologies,such as kerf-free wafering,push towards the goal of grid-parity./GH T OUR FUTURE阳 光 醺 夷 未 来3Growth Methods for Solar WafersHEM/Directional Solidification Large square wafer.Flexible feedstock.Low capital Equipment cost.Low process cost.Highest throughput.Low Oxygen concerT 一 Multi-grains.M-C lifetime:5-20 Efficiency:15-16%CZ Growth Single crystalline Cell efficiency:16-1 to 22%High equipment cost.Round crystals Pseudo-square wafer Limited wafer size.High oxygen concentration.FZ Growth Round crystals Limited wafer size.Most expensive wa Single crystalline Low oxygen concentration.Highest efficiency.High cost process entry.High cost starting silicon.EFG/Ribbon Growth High material utilization.Low oxygen concentratio Low wafering cost.Moderate efficiency.High cost process entry.High carbon inclusion Limited wafer size.Irregular wafer surface Requires unique cell process.Light Induced Degradation(LID)and SolutionsLID problem CZ wafers made of B-doped silicon have problem of LID.Solutions MCZ wafers.Ga-doped P-type CZ-wafers.P-doped N-type CZ-wafers.Mono-crystalline ingot growth with minimum oxygen,eg,protective crucible for CZ,casting method for mono-ingots,etc.o ICO:c(sn)BE 二为 j r j JstmsB-dop Cx$i Gaiop.Cz-Sl P-dop.CX-5i B-dop.MCx-Si1 o ficm 1 2 Qcm 0 6 Qcm 1 2 Ocm。八 14 Ppm(O-T9 pom|O)-16ppn OJ-1 5 ppnChange of minority carrier lifetime of different type of wafers after light soakingAfter J.Schmidt and R.HezelGa-doped P-type5 P-doped N-type wafer technologiesspecifications Ga-doped P-type wafers.P-doped N-type wafers.ItemGallium DopedPhosphorus DopedGrowth MethodCZCZConduction TypePNDopantGa(Gallium)P(Phosphorus)Resistivity0.5-6 Q.Cm0.5-3.5Q.CmOrientation 3Q3QLifetime210Ps2100 usOxygen ContentWl.OX IO】atms/Cm31.OX 1018 atms/Cm3Carbon Content5.OX 1016 atms/Cm35.0X 1016 atms/Cm3Etch PIT DensityW3000/Cm2W3000/Cm26New growth technologies for mono-wafers Other crystallization technologies can be applied for growing silicon mono-crystals,such as Bridgman process.BP Solaris Mono2 TM has advantages of:Close to CZ mono solar cell efficiencyLess oxygen contentUtilize the similar furnace set up as that for multi-crystalline ingots.Much reduced LID(1O6U一79%76%-74%-71%69x69x2367%LDK First G6(800kg)IngotG4G5G6650-800kg400-450kg250-270kgLDK G6 Ingot,800kg13Ingot Characteristics and silicon packingRecharging system for taller ingotsAchieved:盘 Ingot size：69x69x30cmo(25%taller)Ingot weight：330kgo善 Run time：60 hrs。(10%increase)Energy consumption：74%(increase 5%)Throughput：Increase 15%25cmIncrease 15%31cmJ ji;,q.j)DSS furnace with recharging systemSummary Crystalline silicon based solar cells will continue to dominate the market in the years to come.Polysilicon feedstock produced with different technologies will meet the PV demand.Mono-wafers with doping materials other than boron will find their wider applications.Continued technology development on the multi-crystalline based materials will improve the wafer quality and lower down the cost.