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• 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]

Using thermal evaporation, Cu(In,Ga)Se 2 (CIGS) layers were deposited at low temperature (350 °C) and high rate (10 μm/h) using a single stage process. They were then recrystallized using a variety of alkali fluorides: NaF, KF, RbF and CsF. To ensure that the substrate would not influence the study (via alkali diffusion), the samples were deposited on silicon wafers. The chemical, physical and electrical properties of the films were then characterized, demonstrating that all alkali fluorides behave as fluxing agents to enhance recrystallization and conductivity, and induce a (112) preferential orientation. Secondary ion mass spectrometry analysis showed that no modification of the elements' distribution occurs because of recrystallization. Solar cells were also fabricated and characterized, indicating that NaF can double the efficiency of solar cells compared to the as-deposited layers. This enhancement is accompanied by the disappearance of a rollover, voltage dependent current collection and shunt from the current density-voltage curves. However, even for the best recrystallization, the current is still limited to 28 mA/cm2, indicating that only a portion (0.75 μm) of the full device (2 μm) is activated. • Cu (In,Ga)Se 2 layers are recrystallized using a variety of alkali fluorides. • Efficiency of device was doubled for samples recrystallized with NaF. • Observed disappearance of rollover and shunt from the J-V curves [ABSTRACT FROM AUTHOR]