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1、InGaAsN的MBE外延生长技术及太阳能电池制作李景灵李景灵 林云昊林云昊 周仕忠周仕忠 背景InGaP/InGaAs/Ge 三结太阳能电池技术已成熟;提出基于GaAs体系 InGaP/GaAs/x/Ge四结电池材料;新材料的禁带宽度要求:0.951.05eV;InGaAsN材料禁带宽度可在上述范围调整因此:X=InGaAsNX=InGaAsN已知该四结太阳能电池效率值已达43%InGaAsN的MBE生长技术关键技术:N的复合,使得器件的光学和电学性能下降;高质量的InGaAsN薄膜,是从减少N元素对其性能的影响着手的。一般InGaAsN太阳能电池薄膜中N含量不超过2%InGaAsN薄膜优化
2、生长生长温度要低:多数MBE生长方式均在430-500;后退火工艺 低温生长低温生长可以降低受主浓度(降低N对薄膜的消极影响)Acceptor concentration(measured by CV)vs substrate temperature for GaInNAs epilayers and solar cells.A general trend of decreasing acceptor concentration with decreasing substrate temperature is observed后退火工艺可改善晶体质量,提高外量子效率可减少N对薄膜的消极影响,明
3、显提高短路电流密度;J-V characteristics of the InGaAsN DHJSCs under AM 1.5 G illuminationwithout and with post-thermal annealingComparison of the quantum efficiency of the InGaAsN DHJSCs without andwith post-thermal annealing太阳能电池制作工艺利用晶片键合的方法,将基于倒置结构生长的GaInP/GaAs/InGaAs三结太阳和Ge太阳电池单片集成,充分利用Ge电池,既直接作为四结电池的底电池,
4、又作为支撑衬底,实现四结带隙能量分别为1.9/1.4/1.0/0.67eV的太阳电池太阳能电池制作工艺亮点亮点:引入Sb:降低band gap,提高lattice constant于rf-plasma nitrogen sources前方安装偏移盘(Biased deflection plates)太阳能电池制作工艺 太阳能电池制作工艺Sample1:GaInNAs(without the use of deflection plates)Sample2:GaInNAs(DP)(grown using deflection plates)Sample3:GaInNAsSb(grown usin
5、g biased deflection plates)The use of deflection plates has increased the IQE of the GaInNAs cell from 56%to 68%at maximum.The addition of antimony drives the device IQE even higher,reaching 79%at maximum.The absorption edges of the materials closely correspond to the band gaps as measured by PL:GaI
6、nNAs,1.08 eV;GaInNAs(DP),1.03 eV;and GaInNAsSb,0.92 eV.太阳能电池制作工艺(少子寿命少子寿命)GaInNAs film:0.55 nsGaInNAs(DP)film:0.74 ns.GaInNAsSb:0.20 ns 太阳能电池制作工艺太阳能电池制作工艺太阳能电池制作工艺The QEs for the samples with the wide depletion widths are the best reported for a GaInNAs sample,0.96.A report by Li et al on GaInNAs samples with similar bandgaps,but grown by MOCVD,shows maximum QEs below 0.7.Indeed,the best GaInNAs solar cells reported anywhere have had near band-edge QEs of approximately 0.8.