化合物半導體太陽電池之研究

Abstract

本研究室以有機金屬氣相磊晶系統,進行III-V族化合物半導體太陽電 池的研究與開發,所成長的太陽電池結構,包括(1)GaAs及GaInP單接面太陽 電池,(2)AlGaAs/GaAs及GaInP/GaAs異質接面太陽電池,(3)GaAs p-i-n 單 接面太陽電池...等不結構,以期創造出高效率低成本 的太陽電池,並進行 磊晶的研究.經過四年多的努力,我們已經能夠成長出高品質的AlGaAs/ GaAs異質磊晶,並成功的製作出轉換效率高達20%(AM 1.5,1 sun,300K)的 AlGaAs/GaAs異質 接面太陽電池,為全國最高效率的GaAs太陽電池. 除 此之外,本研究室並擬進行GaInP/GaAs雙接面太陽電池的研究,以求技術上 的突破與與開發更高效率的太陽電池.因此除了加強GaInP磊晶品質的提昇 之外,並以數學軟體Mathematica來進行太陽電池的數值模擬,作為磊晶成 長時的參考,以其能創造出理論效率高達34%的GaInP/GaAs雙接面太陽電 池. GaAs solar cell has the advantage of high efficiency and radiation hardness,is suitable for terrestial and space aaplication.In this work,we have fabricatedAlGaAs/GaAs heteroface p-n junction solar cells which were grown by low pressure MOCVD system.The metallization was performed by evaporating Au-Ge for back contact and Au-Be for front contact, the lift-off process of front grid pattern was using image- reversal lithography technique to get thicker front contact easily to minimize series resistance.A Al2O3 layer with suitable thickness was used asanti-reflecting coating to reduce the reflectivity of cell. The efficiency ofour best cell is 19.8% at AM1.5 70mW/cm2,the Jsc,Voc,and fill factor(FF) are17.6mA/ cm2,1.01V,78.23% respectively. The theoretical efficiencies of series-connected,p-n GaInP/GaAs solar cell at near AM0 spectra(using 5800K black-body radition,total power density is 1353W/m2) are also calculated.Under the limitation of current match of top GaInP cell and buttonGaAs cell,optimized top GaInP cell total thickness,emitter thickness,basethickness,emitter doping concentration,and base doping concentation are determined. According to our calculation,the theoretical efficiency of p-n GaInP/GaAstandem solar cell is 27.68% at AM0.