Fabrication Of Cu₂ZnSnS₄ Thin Films By Magnetron Sputtering And Co-electrodeposition

With the decrease of fossil fuels,the energy crisis forced people to look for alternative energies.Among the new energies,solar energy is inexhaustible and considered to be the most promising clean and renewable energy.At present,there are three common thin-film solar cells,CdTe,CIGS(CuIn_x Ga_?1-x?Se₂)and CZTS?Cu₂ZnSn₄?.However,Te,In and Ga are rare metals which are very expensive;Cd is a heavy metal element which is questioned for the safety.CZTS has similar optical and semiconductive properties with CIGS,and all elements are abundant and non-toxic.So CZTS is expected to become an alternative material to replace CIGS.In this thesis,magnetron sputtering and one-step electrodeposition methods were used to fabricate CZTS films.Magnetron sputtering technique can control the composition of CZT metal layer properly and get high quality film.But this method highly depends on the sulfurization process.In this study,sulfurization temperature and SnS content were investigated.Electrodeposition is low-cost and simple.But it's difficult to control the composition during deposition,and it extremely relies on the post annealing process.So during the deposition,the influences of pH value and ionic concentrations were studied.And during the annealing process,the effects of sulfurization time and temperature on the morphology of CZTS were investigated.Thin films were characterized by X-ray fluorescence,Energy disperse spectroscopy,X-ray diffraction and Raman spectroscopy.The surface and cross-sectional images of the films were observed by Scanning electron microscopy.Through the discussion and analysis,we found that in the sputtering method,the CZTS films grew best when the sulfurization temperature was 580?and the SnS content was 8mg.The optimal pH value of the electrodeposition method was 5.7,the best ion concentration was 22mM?CuSO₄·5H₂O?,22mM?ZnSO₄·7H₂O?and 8mM?SnSO₄?.Preheating the CZT precursor at 300?for 30min could improve the morphology of the film.The optimum sulfurization time and temperature was 60min,580?,respectively.The prepared film was dense with uniform grains and the thickness was about 2?m,which was suitable for being used as absorber layer.