Carbon concentration and particle precipitation during directional solidification of multicrystalline silicon for solar cells .pdf

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1、ARTICLEINPRESSJournalofCrystalGrowth310(2008)2192–2197www.elsevier.com/locate/jcrysgroCarbonconcentrationandparticleprecipitationduringdirectionalsolidificationofmulticrystallinesiliconforsolarcellsa,b,aaLijunLiu,SatoshiNakano,KoichiKakimotoaResearchInstituteforAppliedMechanics,Kyushu

2、University,6-1,Kasuga-Koen,Kasuga816-8580,JapanbSchoolofEnergyandPowerEngineering,XianJiaotongUniversity,Xian,Shaanxi710049,ChinaAvailableonline3December2007AbstractThecontentanduniformityofcarbonandsiliconcarbide(SiC)precipitateshaveanimportantimpactontheefficiencyofsolarcellsmadeofmu

3、lticrystallinesilicon.WeestablishedadynamicmodelofSiCparticleprecipitationinmoltensiliconbasedontheSi–Cphasediagram.Couplingwithatransientglobalmodelofheattransfer,computationswerecarriedouttoclarifythecharacteristicsofcarbonsegregationandparticleformationinadirectionalsolidificationpr

4、ocessforproducingmulticrystallinesiliconforsolarcells.TheeffectsofimpuritylevelinsiliconfeedstockandsolidificationprocessconditionsonthedistributionsofsubstitutionalcarbonandSiCprecipitatesinsolidifiedsiliconingotswereinvestigated.ItwasshownthatthecontentofSiCparticlesprecipitatedinsoli

5、difiedingotsincreasesmarkedlyinmagnitudeaswellasinspacewithincreaseincarbonconcentrationinsiliconfeedstockwhenitexceeds1731.2610atoms/cm.ThedistributionofSiCprecipitatescanbecontrolledbyoptimizingtheprocessconditions.SiCprecipitatesareclusteredatthecenter-upperregioninaningotsolidified

6、inafast-coolingprocessbutattheperiphery-upperregionforaslow-coolingprocess.r2007ElsevierB.V.Allrightsreserved.PACS:07.05.Tp;81.10.Fq;85.40.Ry;81.30.FbKeywords:A1.Computersimulation;A1.Directionalsolidification;A1.Impurities;A2.Growthfrommelt;B3.Solarcell1.IntroductionCarbonisoneofthema

7、jorimpuritiesinsiliconfeedstock.WhenthecontentofcarbonexceedsitsMulticrystallinesiliconisthemostwidelyusedmaterialsolubilitylimitinsilicon,itwillprecipitatetoformsiliconinsolarcellsandisnowusedinmorethan50%ofPVcarbide(SiC)particlesinadirectionalsolidificationmodulesworldwide[1,2].Direc

8、tiona