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A pulsed-DC sputtering process at room temperature has been developed for the deposition of the CIGS absorber layer. It uses a single quaternary target and is followed by a high temperature post-deposition annealing process. It has to be particularly noticed that no additional selenium supply was used. The annealed layers have shown a high microstructural quality: micrometric grain size, highly oriented (112) chalcopyrite phase, no phase decomposition and no Cu 2-x Se secondary phase at the surface. The use of such an absorber layer for the fabrication of 0.5 cm 2 solar cells has allowed reaching a conversion efficiency of 11.8% with an open circuit voltage of 558 mV, a short circuit current density of 32.1 mA·cm −2 and a fill factor of 65.8%. [ABSTRACT FROM AUTHOR]

Considering the chalcopyrite solar cell fabrication process, the commonly reported substrate bending effect that is observed after thermal process, in a front side halogen lamp-based annealing configuration (Rapid Thermal Annealing –RTA- equipment), has been investigated. We first proposed a simple model explaining the substrate bending shape dependence on the initial stress state within the molybdenum (Mo) layer (free, tensile or compressive). Then, we showed that it is possible to overcome this issue by simply using a reactive (oxygen based) sputtering process for the deposition of the Mo layer. Finally, we showed that using a bilayer structure Mo(O)/Mo allows a more precise control of the flatness of the annealed samples. To understand the mechanisms governing such changes in substrate bending, structural and morphological material changes as a function of oxygen flow have been investigated by using X-ray diffraction and scanning electron microscope imaging, respectively. The elemental distribution throughout the Mo(O)/Mo bilayer structure thickness was also investigated. [ABSTRACT FROM AUTHOR]

Abstract This work investigates the influence of the ion source (Au+ and Si+2 ions) of liquid metal alloy source-focused ion beam (LMAIS/FIB) on the nanopattering. Two sets of SiO 2 /Si nanopatterns with a width of 450 nm on Silicon on insulator (SOI) substrate are fabricated by 30 keV Au+ and Si+2 ions, respectively. To study this effect, the sputtering yield is calculated using the volume loss method from atomic force microscopy (AFM) profiles obtained for each set. The results of the sputtering yield were compared with theoretical results calculated from Yamamura model for normal incidence for validation. The comparison showed a good agreement between the two results with a relative difference of about 5.3% obtained using Si+2 ions. Highlights • The effect of AuSi LMAIS/FIB ions on nanomilling is investigated experimentally. • This effect has been shown through the study of sputtering yield. • The comparison has shown that Au+ ions are better for stable nanopatterns. • Our experimental results are in good agreement with calculated results. [ABSTRACT FROM AUTHOR]

Aluminum doped-zinc oxide (AZO) thin films were prepared on glass substrate by radio-frequency (RF) sputtering at room temperature. The sheet resistance, R sh [Ω] the resistivity, ρ [Ω·cm] and the 1/ f noise were studied as a function of thickness, t from 50 nm to 450 nm. The eddy current characterized the homogeneity of AZO thin films. The surface morphology has been analysed by atomic force microscopy (AFM). The 1/ f noise is normalized with respect to the bias, frequency and unit area, and C us is proportional to the sheet resistance R sh . Two configurations were used to characterize material and contact noise. The pressure effect of four point-probe on the material and the contact noise were also investigated. Our results show that the homogeneity of the samples increases as the film thickness increases and the resistivity decreases with increasing thickness and reaches the lowest value of 1 × 10 − 3 Ω cm at 450 nm. The average grain size and the root-mean-square roughness increases with rising thickness. The ratio K = C us / R sh is proportional to t 2 , which indicates that the mobility and the noise parameter α H shrink with the shrinkage of the thickness. [ABSTRACT FROM AUTHOR]

In this investigation, the mechanical properties of the different layers composing a CuIn 1 − x Ga x Se 2 (CIGS) based solar cell were studied. Magnetron sputtering technique was used for the deposition of these layers except for the cadmium sulphide (CdS) layer which was deposited using chemical bath deposition process. We performed several indentation tests on the individual layers, i.e. molybdenum (Mo) back contact layer, CIGS absorber layer, CdS and alternative zinc sulphide oxide (ZnOS) buffer layers, and zinc oxide (ZnO)-AZO (aluminium-doped zinc oxide) transparent window layer; all were deposited on glass substrates. We report the values of the hardness ( H ) and of the Young's modulus ( E ) for each material, using indentation tests and an analytical model. The Mo layer remained the hardest and the most rigid, with H = 8.7 GPa and E = 185 GPa, while the CIGS layer has shown poor mechanical properties with H = 3 GPa and E = 58 GPa. On the other hand, the observed similarity in mechanical properties of the ZnO and ZnOS layers might be attributed to the similarity of their microstructures. [ABSTRACT FROM AUTHOR]