In situ ellipsometric study of the three‐stage process in CuInSe2 film deposition

Abstract

AbstractIn Situ ellipsometric study has been carried out during the deposition of the CuInSe2 thin film by means of the three‐stage process. A rotator analyzing ellipsomerter using a 632.8 nm He‐Ne laser was used. Ellipsometric parameters (Ψ and Δ) and reflectivity R was obtained during the entire deposition stages, in which a complex reflection coefficient is ρ=tanΨ exp(iΔ). Cu, In and Se were deposited on the Mo‐coated SLG substrate. At the first‐stage (In‐Se deposition), the In‐Se film deposition rate and its reflactive index has been obtained on the basis of the light interference. At the second‐stage, changes in both Ψ and Δ are observed. Based on the X‐ray diffraction measurement, these changes are related to the stoichiometric composition of the film from In‐rich to Cu‐rich. This signal was utilized as a process switch from the second‐stage to the third‐stage. At the third stage, the weak change in Ψ has been observed showing the change of the stoichiometric composition from the Cu‐ rich to the In‐rich. By means of the in situ ellipsometry‐controlled three‐stage process, the CuInSe2 layer with single phase chalcopyrite structure has successfully been prepared, which exhibits an intense near‐band‐edge photoluminescence at 0.998 eV at room temperature. The preliminary fabricated ZnO/CdS/CuInSe2 solar cell exhibited a conversion efficiency of 5.6%. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)