n型单晶硅太阳电池中硼离子注入发射极特性研究
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摘要
离子注入以其掺杂均匀可控、便于图形化掺杂及简化太阳电池生产工艺的特点在光伏界引起广泛的关注,但同时也存在着注入缺陷难以消除的缺点。该文通过对硼注入发射极退火特性进行研究,发现样品的J_(0e)(发射极饱和电流)、少子寿命t_(eff)、Imp_V_(oc)(理论开路电压)均随退火温度的升高得到显著改善。为进一步研究其机理,采用椭圆偏振光光谱对晶格损伤进行表征,并借助TCAD软件模拟分析注入后热处理所产生的硼硅团簇(BIC)等缺陷状态,从损伤修复和杂质激活两方面对硼(B)注入发射极J_(0e)随退火温度变化的机制做出解释。
Ion implantation technique attracts great interests in PV industry recent years for its uniformly controlled doping,convenient patterned doping and simplified solar cell processes. However,the disadvantage of the technique is that the defects caused by ion implantation are difficult to eliminate. In this paper,the annealing temperature of boron ion implantation emitters was studied. It can be found that the J_(0e),lifetime and Imp_V_(oc)of ion implanted emitters are improved markedly along with the annealing temperature increase. For further investigation,using spectroscopic ellipsometry to characterize the lattice damage and TCAD software simulation,the defects such as boron interstitial clusters(BIC) formed during annealing after ion implantation is analyzed. The mechanism of J_(0e)changing with annealing temperature is explained by two aspects of lattice damage repair and dopants activation.
Ion implantation technique attracts great interests in PV industry recent years for its uniformly controlled doping,convenient patterned doping and simplified solar cell processes. However,the disadvantage of the technique is that the defects caused by ion implantation are difficult to eliminate. In this paper,the annealing temperature of boron ion implantation emitters was studied. It can be found that the J_(0e),lifetime and Imp_V_(oc)of ion implanted emitters are improved markedly along with the annealing temperature increase. For further investigation,using spectroscopic ellipsometry to characterize the lattice damage and TCAD software simulation,the defects such as boron interstitial clusters(BIC) formed during annealing after ion implantation is analyzed. The mechanism of J_(0e)changing with annealing temperature is explained by two aspects of lattice damage repair and dopants activation.
引文
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[12]Kane D E,Swanson R M. Measurement of the emitter saturation current by a contactless photoconductivity decay method[A]. IEEE Photovoltaic Specialists Conference[C],St. Louis,US,1985.
[13]Hermle M,Benick J,Rüdiger M,et al. n-Type silicon solar cells with implanted emitter[A]. 26th European Photovoltaic Solar Energy Conference[C],Hamburg,Germany,2011.
[14]Pawlak B J,Janssens T,Singh S,et al. Studies of implanted boron emitters for solar cell applications[J].Progress in Photovoltaics:Research and Applications,2012,20(1):106—110.
[15]Lioudakis E,Christofides C,Othonos A. Study of the annealing kinetic effect and implantation energy on phosphorus-implanted silicon wafers using spectroscopic ellipsometry[J]. Journal of Applied Physics,2006,99(12):123514.
[16]Fried M, Lohner T, Aarnink W A M, et al.Nondestructive determination of damage depth profiles in ion-implanted semiconductors by spectroscopic ellipsometry using different optical models[J]. Journal of Applied Physics,1992,71(6):2835—2843.
[17]De Salvador D, Napolitani E, Bisognin G, et al.Experimental evidences for two paths in the dissolution process of B clusters in crystalline Si[J]. Applied Physics Letters,2005,87(22):221902.
[18]Mirabella S,Bruno E,Priolo F,et al. Dissolution kinetics of boron-interstitial clusters in silicon[J].Applied Physics Letters,2003,83(4):680—682.
[19]Luo Xuan,Zhang S-B,Wei Su-Huai. Understanding ultrahigh doping:The case of boron in silicon[J].Physical Review Letters,2003,90(2):026103.
[2]Minnucci J, Kirkpatrick A, Matthei K. Tailored emitter,low-resistivity,ion-implanted silicon solar cells[J]. IEEE Transactions on Electron Devices,1980,27(4):802—806.
[3]Spitzer M B,Tobin S P,Keavney C J. High-efficiency ion-implanted silicon solar cells[J]. IEEE Transactions on Electron Devices,1984,31(5):546—550.
[4]Rohatgi A,Meier D L,McPherson B,et al. Highthroughput ion-implantation for low-cost high-efficiency silicon solar cells[J]. Energy Procedia,2012,15(1):10—19.
[5]范玉杰,韩培德,梁鹏,等.效率达19.1%的全离子注入单晶硅太阳电池[J].太阳能学报,2015,36(4):829—834.[5]Fan Yujie,Han Peide,Liang Peng,et al. All-ionimplanted singel crystalline silicon solar cells up to efficiency of 19.1%[J]. Acta Energiae Solaris Sinica,2015,36(4):829—834.
[6]Liang Peng, Han Peide, Fan Yujie, et al. Boron implanted emitter for n-type silicon solar cell[J].Chinese Physics B,2015,24(3):447—452.
[7]刘志锋,张峰,殷磊,等.利用离子注入技术改善晶硅太阳能电池性能[A].第12届中国光伏大会暨国际光伏展览会论文集[C],北京,2012,1—7.[7]Liu Zhifeng,Zhang Feng,Yin Lei,et al. Improvement of crystalline silicon solar cells using ion implantation technique[A]. CPVC12 Proceedings[C], Beijing,2012,1—7.
[8]Benick J,Müller R,Bateman N,et al. Fully implanted n-type PERT solar cells[A]. 27th EU PVSEC Proceedings[C],Durban,South Africa,2012.
[9]Boo H,Lee Jong-Han,Kang Min-Gu,et al. Effect of high-temperature annealing on ion-implanted silicon solar cells[J]. International Journal of Photoenergy,2012,special p1:1—6.
[10]Lanterne A,Gall S,Veschetti Y,et al. High efficiency fully implanted and co-annealed bifacial n-type solar cells[J]. Energy Procedia,2013,38:283—288.
[11]Ok Young-Woo,Upadhyaya A D,Rounsaville B,et al.High Implied Voc(>715 m V)and low emitter saturation current density(~10 fA/cm2)from a lightly B doped implanted emitter[A]. 2015 IEEE 42ed Photovoltaic Specialist Conference(PVSC)[C],New Orleans,LA,2015.
[12]Kane D E,Swanson R M. Measurement of the emitter saturation current by a contactless photoconductivity decay method[A]. IEEE Photovoltaic Specialists Conference[C],St. Louis,US,1985.
[13]Hermle M,Benick J,Rüdiger M,et al. n-Type silicon solar cells with implanted emitter[A]. 26th European Photovoltaic Solar Energy Conference[C],Hamburg,Germany,2011.
[14]Pawlak B J,Janssens T,Singh S,et al. Studies of implanted boron emitters for solar cell applications[J].Progress in Photovoltaics:Research and Applications,2012,20(1):106—110.
[15]Lioudakis E,Christofides C,Othonos A. Study of the annealing kinetic effect and implantation energy on phosphorus-implanted silicon wafers using spectroscopic ellipsometry[J]. Journal of Applied Physics,2006,99(12):123514.
[16]Fried M, Lohner T, Aarnink W A M, et al.Nondestructive determination of damage depth profiles in ion-implanted semiconductors by spectroscopic ellipsometry using different optical models[J]. Journal of Applied Physics,1992,71(6):2835—2843.
[17]De Salvador D, Napolitani E, Bisognin G, et al.Experimental evidences for two paths in the dissolution process of B clusters in crystalline Si[J]. Applied Physics Letters,2005,87(22):221902.
[18]Mirabella S,Bruno E,Priolo F,et al. Dissolution kinetics of boron-interstitial clusters in silicon[J].Applied Physics Letters,2003,83(4):680—682.
[19]Luo Xuan,Zhang S-B,Wei Su-Huai. Understanding ultrahigh doping:The case of boron in silicon[J].Physical Review Letters,2003,90(2):026103.