Chalcopyrite phase

The XRD pattern for the as-deposited film depicted in Eigure 1.5a shows the main characteristic reflexes of the chalcopyrite phase, but the peaks are broad, indicating poor crystallinity. The optoelectronic properties of the as-deposited films are also poor (see Section 1.3). A narrowing of the reflexes in the XRD pattern is observed after annealing the film (Figure 1.5b), confirming the improvement in crystallinity. 

Fig. 195. Cui, Ini, Zn2,Te2. Lattice constant vs. composition. For chalcopyrite phases (0 x g 0.1), the effective cubic lattice constant

Segregated phases, other than the target material, usually found on the surface of deposited polycrystalline chalcopyrite semiconductor films, such as CuInSc2 and CuInS2, constitute a shortcoming in material quality for solar cell and other applications. In fact, these films are usually prepared purposefully with an excess of... 

Unidentified Fe-S-Si phases Chalcopyrite, CuFeS2 Amorphous silica, SiC>2 Elemental sulfur, S Goethite, etc., FeOOH... 

Vapor and brine from the Brandon vent of the East Pacific Rise have identical Fe isotope compositions, implying that phase separation does not produce an isotopic fractionation (Beard et al. 2003a). The role that sulfide precipitation plays in controlling the Fe isotope composition of the fluid remains unknown. The precision of the two sulfide analyses reported by Sharma et al. (2001) was not sufficient to resolve if sulfide precipitation would produce Fe isotope fractionation in the vent fluid. In a detailed study of sulfldes from the Lucky Strike hydrothermal field from the mid Atlantic Ridge, however, Rouxel et al. (2004) found that sulfldes span a range in 5 Fe values from -2.0 to +0.2%o, and that pyrite/marcasite has lower 5 Fe values ( l%o) as compared to chalcopyrite. The variations in mineralogy and isotope composition are inferred to represent open-system equilibrium fractionation of Fe whereby... 

Figure 2.14 Electrochemical phase diagram for chalcopyrite with elemental sulphur as metastable phase. Equilibrium lines (solid lines) correspond to dissolved species at 10 mol/L. Plotted points show the upper and lower limit potential of collectorless flotation of chalcopyrite reported from Sun (1990), Feng (1989) and Trahar (1984)...

Figure 4.30 Electrochemical phase diagram for the butyl xanthate/oxygen system and the observed lower and upper ( ) limiting flotation potential of galena and chalcopyrite at which flotation recovery is greater than 50% (EX 2 xlO mol/L)...

Five different vein phases (Types i to V) are recognized at both deposits, aii have variabie amounts of carbonates and quartz gangue. Type i veins contain oniy brecciated quartz and carbonate minerals and at ED are spatially associated with disseminated arsenopyrite, chalcopyrite, pyrrhotite, and pyrite in the mafic host rock. Type II veins in both deposits are partly brecciated and contain 5-80% sulfides of dominantly pyrite, arsenopyrite, and at GB chalcopyrite. Type III veins are quartz-calcite-tetrahedrite-bismuthinite microveins that cut both Types I and II veins. The fine-grained sulfides replace and enclose arsenopyrite and pyrite in Type II veins and are also visible in microfractures within the Type II sulfides. Type IV veins are base-metal rich and characterized by galena, sphalerite, chalcopyrite, pyrite, and stibnite with a maximum width of 20 cm. The Type V veins are late barren-carbonate veins cutting all previous veins and textural features. 

A note of caution is necessary when deahng with these materials. It is not trivial to distinguish between CuInS(Se)2 and some phases of Cu—S(Se). Diffraction and optical properties may be similar. Elemental analysis is particularly important to verify inclusion of indium in the films and in the correct ratio. A fingerprint of the chalcopyrite XRD is the presence of a weak peak at 26 = 17-18°, corresponding to the (101) chalcopyrite reflection. This is often not seen, although this could be either because the deposit is not chalcopyrite or because weak peaks are usually not seen in nanocrystaUine materials with particularly small crystal size. 

Overall, it appears likely that the films contained chalcopyrite CuInSi mixed with other phases with similar diffraction patterns. Separate microstrac-tural characterization (EDS) of films with varying composition (ca. 10% excess Cu or In) showed the formation of separate phases of CuiS and IniSs, respectively, along with the CuInSi [39]. The best films were obtained at high deposition temperatures (80°C) and with stirring. Lower deposition temperature resulted in poorer stoichiometry (less S), and stirring improved fihn uniformity. Grain size, measured by TEM (which does not necessarily show crystal size) was 100 00 nm. 

I1-VI-V2 chalcopyrite DMS, (Cd JtMn t)GeP2 was prepared by the solid phase chemical reaction. Mn vacuum deposition (30 nm) on a single crystal of CdGeP2 and the reacting process (500°C, 30 min) was carried out in an MBE chamber (Medvedkin et al. 2000). The Mn/Cd composition ratio decreases rapidly with the depth. The average... 

The most prevalent ternary chalcopyrite materials are p-type Cu(In Ga)(S Se)2 (CIGS), which crystallize in the tetragonal chalcopyrite stmcture and are used in the photovoltaic modules. The complexity of the phase diagrams for Cu-III-VI materials results in a large number of intrinsic... 

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