The Research Of Sige:h Alloy Thin Film By Rf-pecvd And Its Application In Solar Cell

Because of the high absorption coefficient and the narrow band gap(1.1~0.66eV) ofsilicon-germanium(SiGe) thin film,it has the ability to expand absorption of solar spectrum andimprove the conversion efficiency of the solar cells. And the SiGe thin films in the triplejunction solar cells have good structure and have the ability to improve the efficiency andstability. So it has attracted a great deal of research interesting for solar cells application.The silicon-germanium thin films used in this study were fabricated by RF-PECVD system.Several series of silicon-germanium thin films fabricated under different substrate temperatures,discharge powers, hydrogen dilutions, germane concentrations, reactive pressures, distance ofelectrode and so on have been studied. The results indicated that the dark conductivity increasedwith the increase of substrate temperature and germane concentrations, and the decrease ofreactive pressures and hydrogen dilutions. However, the photosensitivity increased with theincrease of discharge power and substrate temperature, and the decrease of germaneconcentrations and hydrogen dilutions. The amorphous SiGe thin films materials with 5×105photosensitivity have been manufactured when temperature was 175℃,germane concentrationwas 5%,hydrogen dilutions was 24,total flux was 200sccm,reactive pressure was 3Torr,discharge power was 90W. The amorphous SiGe thin films deposition rate was 0.08nm/s. Themicrocrystalline SiGe thin films materials with 2×104 photosensitivity have been manufacturedwhen temperature was 175℃,germane concentration was 1.4%,hydrogen dilutions was 82,totalflux was 400sccm,reactive pressure was 3Torr,discharge power was 60W. The microcrystallineSiGe thin films deposition rate was 0.04nm/s and theχc was 41%.The properties of SiGe thin films solar cells were studied on the basis of the achievements Ihad attained in the materials properties. The relationship between the performances of SiGe thinfilms solar cells and the materials properties were studied. The structure of thin silicongermaniumfilm solar cells was glass /SnO2 /p-a-Si:H /i-ａ-SiGe:H /n-nc–Si:H /Al. Theconversion efficiency with 4.29% was achieved.To optimize SiGe thin film solar cells the buffer layers especially at the p/i interface were studied, and after the optimization of the buffer layer inp/i surface the FF rise to 53% from 46% and finally the efficiency rise to 4.99%.