The Study On Performance Of ZnS Film By CBD

In the global scope, the energy crisis and the traditional energy of the environment bypollution is more serious, develop clean environmental protection and energy into a humanfacing the most important topic. Copper indium gallium selenium （CIGS） compound filmsolar cells with its better optical gap （Eg），high conversion efficiency, better long-termstability, resist radiation ability become photovoltaic industry advantages research hotspot.The traditional CIGS solar cells were typically fabricated using a cadmium sulfide （CdS）buffer layer by chemical bath deposition （CBD），and get better efficiency of conversion，butin the process of production, the environment was serious pollution by Cd emissions, and thequantum efficiency of a CdS/CIGS solar cell drops at short wavelength due to opticalabsorption losses from CdS layer. In order to get no cadmium buffer layer people do a lot ofexperiments, ZnS is non-toxic, cheap, wide band gap （3.8eV）, etc.Chemical bath deposition preparation ZnS films, technology simple, easy to control theexperimental conditions, the experiment is in alkaline conditions, the reaction solution ismade of ZnSO₄, NH₄OH and SC（NH₂）₂, ZnS thin films were deposited,through the XRD、TEM、SEM、steps meter、EDS and XPS，to inspection and analysis the films, study the bestpreparation process. The results found that Water bath temperature and deposition timetechnological conditions of the film through rate, ZnS structure, thickness and surfacemorphology and so on all have influence. And the optimal concentrations of ZnSO₄, thiourea,ammonia were0.025M,0.27M,2.9M, respectively, with deposition120min at80℃. In theseconditions, the ZnS film surface appeared a lot of white particles, and were equably arranged,the surface of ZnS film is smooth. XRD tests showed that ZnS film is amorphous state,transmissivity was more70%in λ>550nm, film thickness was about102nm. Afterair-annealing under300℃, the peaks unchanged and some tiny microcrystallin were appear.TEM diffraction spot diameter to calculate the crystal plane spacing （0.31nm） corresponded tothe cubic structure of ZnS （111）. XPS tests showed that we find the peak of Zn2p3/2and S2phave happened to the chemical displacement, move to higher can direction; Zn2p3/2and S2pspectrum peak intensity increased, the microscopic defect was increase with annealing.Theforbidden band width of CBD-ZnS greater than powdered ZnS. The forbidden band widthdecreases.