Optical And Electrical Characteristics Of Hydrogenated Amorphous Silicon Carbide Films Prepared By RF Plasma-Enhanced Chemical Vapor Deposition System

At present, crystalline Si solar cells are commonly used on the business and thegoal of improving the photoelectric conversion efficiency and reducing the cost of thecells has always been studying. Preparation of the anti-reflection passivation iflm withexcellent performance is one of the most important methods in the production ofhigh-efficiency and low cost crystalline silicon solar cells. In this paper, a newanti-reflection and passivation filmhydrogenated amorphous silicon carbide(a-SiCx:H) thin iflms were grown by a radio frequency plasma enhanced chemicalvapor deposition (RP-PECVD) system with the reactive precursors of methane (CH4)and silane (SiHj) gases and H】was used as carirer gas to dilute CH4and S1H4. It isvery important for improving the eiffciency of solar cells to research the structurecharacteristics and performance of anti-reflection and passivation of the iflm.First，the effects of RF-PECVD deposition conditions of the ratio of methane tosilane (/?)，substrate temperature (Ts) and RF power density (Pd) on the opticalproperties and microstructural characteirstics of a-SiCx:H thin films weresystematically investigated. Secondly, The best refractive index (w=2.35) of EVAencapsulated crystalline Si solar cells is used as reference.The optimal expeirmentalconditions of preparing a-SiCx:H thin films was obtained by orthogonal experiment.The optical properties of a-SiCx:H thin iflm was compared with that of a-SiNx:H thinfilm, the main researching results are as follows:1. the effects of RP-PECVD deposition conditions on the properties of a-SiCx:H thin films were investigatedWhen the Pd^P and Ts were fixed, it was found that R had a large impacton n andEg. The growth rate and n of the a-SiCx:H thin films decreasedwith凡while the^increased with R, The a-SiCx:H thin iflm grown at higher R was found to besmoother than that grown at lower R. The all minority carrier lifetimes of a-SiCx:Hthin films increased with different Rt but were aifected slightly. When the Pj，P and Rwere ifxed, the growth rate of the a-SiCx:H thin iflms decreased with TS7while their nincreased with Ts. It was found that Eg slightly increased with TSi and the film becamerougher at higher Ts. The minority carrier lifetimes of a-SiCx:H thin films firstincreased, then decreased with the increase of7j,andhad the maximum at7V=320oC.When Ts, P and R were fixed, the growth rate of a-SiCx:H thin films increased withthe Pd while their n only slightly increased and Eg slightly decreased with the Pj. Theminority carrier lifetimes of a-SiCx:H thin iflms first increased, then decreasedincreasing with P^andhad the maximum at Pj=0.l6W/2cm. Pd had the largest effecton the Rq and minority carrier lifetimes of a-SiCx:H thin iflms compared with thegrowth conditions of Ts and R.2, Researching the performance of anti-reflection of a-SiCx:I I thin films.The optimal experimental conditions of prepared optimization anti-reflective thinfilms by PECVD were: R=2, TS=320°C and/V=0」6W/2cm. They both had theperformance of anti-reflection when the a-SiCx:H thin film deposited with the optimalexperimental conditions compared with a-SiNx:H thin film. The a-SiCx:H thin filmhad better performance of anti-reflection than a-SiNx:H thin iflm because of highertransrnittance and lower reflectance.