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• Crystallization temperature range independent of treatment and substrate. • Crystallization rate increases with Na 2 O and an InCl 3 solution treatment. • InCl 3 necessary for grain size enhancement. Amorphous CuInSe 2 films were deposited by rf-magnetron sputtering onto soda-lime glass and silicon substrates. Some were treated with an InCl 3 solution. The films were annealed in a nitrogen environment and studied using in-situ high-temperature x-ray diffraction. CuInSe 2 recrystallization began at ∼x223C270 °C and all samples showed increasing crystallinity up to ∼x223C380 °C. The onset and completion temperatures for crystallization varied minimally between samples. The as-deposited films (no InCl 3) showed CuSe phase formation at intermediate temperatures (180–250 °C). Na 2 O from the soda-lime glass increased net rate of crystallization. InCl 3 resulted in an even greater increase to crystallization rate and largely improved the final crystalline quality. [ABSTRACT FROM AUTHOR]

• InCl 3 used to recrystallize Cu(In,Ga)Se 2 films at low temperature. • Large grains are obtained for temperature as low as 450 °C. • The films become overall indium rich with an indium rich surface. • The alkali profile is modified. One of the key challenges to promote the economic viability of Cu(In,Ga)Se 2 (CIGS) solar cells is the multi-stage co-evaporation process required to make a high quality absorber layer. One phenomenon of interest is dynamic recrystallization using a fluxing agent. While these techniques have significantly improved material systems like CdTe, their impact on other nonmetallic systems are relatively unexplored. In this paper, we demonstrate that InCl 3 can be used effectively to recrystallize CIGS for temperature as low as 450 °C, but that it also induces a modification of the surface composition. Analyses, notably via glancing incidence X-ray diffraction and secondary ion mass spectrometry, show an indium enriched surface as well as a modified alkali profile. [ABSTRACT FROM AUTHOR]

Cu(In,Ga)Se2 (CIGS) thin films were deposited at low temperature (350 °C) and high rate (10 µm/h) by a single stage process. The effect of post-deposition treatments at 400 °C and 500 °C by indium bromide vapor were studied and compared to the effect of a simple annealing under selenium. Structural, electrical, and chemical analyses demonstrate that there is a drastic difference between the different types of annealing, with the ones under indium bromide leading to much larger grains and higher conductivity. These properties are associated with a modification of the elemental profiles, specifically for gallium and sodium. [ABSTRACT FROM AUTHOR]

Cu(In,Ga)Se2 (or CIGS) thin films and devices were fabricated using a modified three-stage process. Using high deposition rates and a low temperature during the process, a copper chloride vapor treatment was introduced in between the second and third stages to enhance the films properties. X-ray diffraction and scanning electron microscopy demonstrate that drastic changes occur after this recrystallization process, yielding films with much larger grains. Secondary ion mass spectrometry shows that the depth profile of many elements is not modified (such as Cu, In and Se) while others change dramatically (such as Ga and Na). Because of the competing effects of these changes, not all parameters of the solar cells are enhanced, yielding an increase of 15% in the device efficiency at the most. [ABSTRACT FROM AUTHOR]

In this work, the diffusion process of sodium (Na) in molybdenum (Mo) thin films while it was deposited on soda lime glass (SLG) was studied. A small amount of oxygen was present in the chamber while the direct-current (DC) magnetron sputtering was used for the deposition. The substrate temperatures were varied to observe its effect. Such molybdenum films, with or without oxidations, are often used in thin film solar cells, either as back contact or as hole transport layers. Secondary ion mass spectrometry (SIMS) was used to quantify the concentration of the species. A grain diffusion mechanistic model incorporating the effect of grain and grain boundary geometrical shape and size was developed. The model was used to provide an in-depth theoretical analysis of the sodium diffusion in molybdenum thin films that lead to the measured SIMS data. It was observed that not only diffusion coefficients should be considered when analyzing diffusion processes in thin films but also the ratio of grain boundary size to grain size. Both depend on substrate temperature and directly affect the amount of diffused species in the film. The data were analyzed under the light of the film growth speed versus diffusion front speed, the effect of oxygen content, and the effect of substrate temperature on the overall diffusion process. The temperature inversely affects the ratio of grain boundary size and grain size and directly affects the diffusion coefficient, which leads to a preferable temperature at which the highest amount of alkali can be found in the film. [ABSTRACT FROM AUTHOR]