Effect of deviations from stoichiometry on electrical conductivity and photoconductivity of CuInSe2 crystals

Compound Copper Chalcogenide Nanocrystals

“…These small deviations in composition can produce large changes in the electrical properties, as well as in the band gap and electronic band structure . Moreover, Cu rich films are found to mostly exhibit p-type conductivity, but as the films become In-rich, a conversion to n-type conductivity occurs . Some of these In-rich structures likely result from the reduced formation energies of cation vacancy sites in the chalcopyrite phase and others as the result of energetically stabilized defect pairs; thus, defects are an important topic in the Cu−In−Se system. , At present, there is no agreement between the numerous studies of these In-rich materials on the phase boundaries’ compositions, on the various phases that lie between CuInSe 2 and CuIn 5 Se 8 , or on their crystal structures …”

Growth and Analysis of Nanostructured CuInSe2-ZnIn2Se4 Solid Solutions: Their Electrical and Photoelectrical Properties

“…are Cu-deficient, the concentration of antisite defects CuIn decreases with increasing x. CuIn substitutional defects create acceptor levels located 0.05-0.08 eV above the valence band [15,19]. In Fig.…”

“…This is evidenced by the strong dependence of Nf values (and thus the concentration of VCu) on the composition of material. According to[19], in CuInSe2 compounds VCu create acceptor levels located 0.7 eV above the valence band. By growing temperature above 110 K, the Fermi level moves up, approaching the donor levels having activation energies of ~0.018 eV and ~0.04 eV.…”

“…It should be noted that the substitutional defects InCu and CuIn are always present in CuInSe2 single crystals. According to Ref [19],. InCu and CuIn are formed due to the phase transition of CuInSe2 from sphalerite to chalcopyrite structure after crystallization and cooling down to room temperature.…”

Unusual electronic transport in (1 −x)Cu2Se–(x)CuInSe2hierarchical composites

“…This trend is valid at all temperatures between 300 and 773 K, suggesting the thermal stability of the microstructure of (1 À x)Cu 2 Se/(x)CuInSe 2 composites within this temperature window. While the initial drop in the electrical conductivity of samples with x # 45% can be anticipated from the incorporation of a poorly conductive secondary phase within a highly conductive matrix, 24,[32][33][34][35][36] the observed sudden large increase for the 48 mol% and 50 mol% CuInSe 2 , suggests either the formation of a new phase, such as Cu 3 InSe 3 , with a different molecular structure and thus different electronic band structure, or a sharp alteration of the electronic band structures of both Cu 2 Se and CuInSe 2 phases, owing to their multiscale hierarchical integration within the (1 À x)Cu 2 Se/(x)CuInSe 2 composites. The former hypothesis can be ruled out, because the XRD, SEM and TEM only show the coexistence of Cu 2 Se and CuInSe 2 phases in the sample with x ¼ 50% and the Cu 3 InSe 3 phase is absent below 1180 K from the Cu 2 Se-CuInSe 2 pseudo binary phase diagram (Fig.…”