Structural Properties of CuIn₃Se₅ and Influence of Growth Conditions

Abstract

Polycrystalline samples of CuIn3Se5 have been synthesized by reaction of stoichiometric mixture of the constituents in evacuated quartz ampoules, in a vertical furnace and in an horizontal one. The composition has been studied by EDAX and Atomic Absorption Spectroscopy. Important deviations in composition have been measured. The structure has been analyzed by X-ray Powder Diffraction, existing mainly single phase. Two spatial groups (SG) have been attributed to CuIn3Se5 by the Rietveld refinement: I 4̄2m (Stannitetype structure) and P 4̄2c (P-chalcopyrite). However, only the refinement in the SG P 4̄2c provides occupation numbers in the lattice that are coherent with the composition determined by EDAX. The discrepancy index, especially the goodness of fit, are smaller for the SG P 4̄2c.

Ion migration in CuIn3Te5single crystal

“…In each disc, the composition, the crystal structure and the electrical and optical properties have been analysed. We conclude that the compound presents a P-chalcopyrite structure, spatial group P 42c, similar to the group in CuIn 3 Se 5 [8,9] with high stoichiometric deviation. Micro-Raman spectra and infrared measurements confirm the presence of the crystallographic phase of CuIn 3 Te 5 with a highly ordered Te sublattice and disordered Cu and In sublattices.…”

The n-Cu0.9Ag0.1In3Se5chalcopyrite, electronic as well as ionic conductor

“…We conclude that it is P-chalcopyrite, similar to CuIn 3 Se 5 [8,9]. For this structure, the occupation numbers in the 8n, 2b, 2e, 2f and 2d positions are 0.9Se, 0.57In+0.02Cu, 0.68Cu, 0.60In+0.02Cu and 1.00In, respectively (10%, 41%, 32%, 38% and 0% of structural vacancies) [9]. Therefore, the 2b and 2f positions present principally the higher number of structural vacancies that correspond to the In site.…”

“…A CuIn 3 Te 5 single crystal with n-type conduction was grown by the vertical Bridgman method, where the electrical and optical properties were analysed and the structure was studied by x-ray diffraction [24]. We conclude that it is P-chalcopyrite, similar to CuIn 3 Se 5 [8,9]. For this structure, the occupation numbers in the 8n, 2b, 2e, 2f and 2d positions are 0.9Se, 0.57In+0.02Cu, 0.68Cu, 0.60In+0.02Cu and 1.00In, respectively (10%, 41%, 32%, 38% and 0% of structural vacancies) [9].…”

“…The ABC 2 chalcopyrites (A = Cu, Ag, B = In, Ga and C = S, Se, Te) present similar structure [29][30][31]: therefore, the n-Cu 0.9 Ag 0.1 In 3 Se 5 semiconductor will present the same p-chalcopyrite structure as the CuIn 3 Se 5 and CuIn 3 Te 5 compounds, where the Ag ions substitute Cu ions in their lattice sites [8,9,25]. This structure type has a high structural vacancy number and the ion jump can be permitted in their sublattice [24].…”

“…The I-III-VI 2 compounds crystallize in the chalcopyrite structure, space group (S.G.) I 42d [4,5]. For the structure of CuIn 3 Se 5 , several models have been proposed such as stannite-type structure, (S.G.) I 42m [6,7], tetragonal structure, (S.G.) P 42c, identified as P-chalcopyrite-type [8,9] and chalcopyrite structure with an ordered defect structure [10]. In all these structures, the materials retain the basic structure over a range of compositions around the ideal one and present stoichiometric deviations.…”