Effect of Zinc Incorporation in CuInS₂Thin Films Grown by Vacuum Evaporation Method

Abstract

Structural, optical and electrical properties of Zn-doped CuInS2 thin films grown by double source thermal evaporation method were studied. Evaporated thin films were grown from CuInS2 powder by vacuum evaporation using resistively heated tungsten boats. The element Zn was evaporated from a thermal evaporation source. The amount of the Zn source was determined to be 0-4% molecular weight compared with CuInS2 source. The effects of Zn on films properties were investigated using X-ray diffraction, optical transmission and reflection spectra. The films were annealed in vacuum at 260• C for 2 h. The Zn-doped samples have band-gap energy of 1.474-1.589 eV. We found that the Zn-doped CuInS2 thin films exhibit p-type conductivity and we predict that Zn species can be considered as suitable candidates for use as doped acceptors to fabricate CuInS2-based solar cells.

Effect of zinc doping and temperature on the properties of sprayed CuInS2 thin films

“…Improved optical transmission property is observed in the IR regions than the films obtained from vacuum and thermal evaporation methods [43,44] (which are not reported by other researchers). Nearly 70% of light transmission occurs in the IR regions when the substrate temperature is at 300 1C and it increases and reaches 90% as the temperature increases from 325 to 350 1C.…”

“…It is attributed to the Zn atoms that occupy sulfur, Cu and other vacancies created by substrate temperatures. Further, the Zn atoms are localized near the surface as well as in the volume of the material [43]. The decrease in film thickness (Table 2) due to the rearrangement of atoms in the films may also be the reason for better transmittance.…”

Strongly Fluorescent Quaternary Cu–In–Zn–S Nanocrystals Prepared from Cu1-xInS2 Nanocrystals by Partial Cation Exchange

“…From the structural characterization, we may reasonably exclude the formation of a shell and the reduction of the core size. Thus, the blue shift can be attributed to the widening of the band gap due to the entrance of zinc ions into the CIS structures, as already observed in doping CIS thin films with zinc and in Cu–In–Zn–S solid solutions. , On the other hand, we cannot completely exclude a not homogeneous Zn distribution inside the CIZS NCs. Unfortunately, the sizes of the present NCs were too small for allowing a compositional profile in the TEM (see the Supporting Information for more details on this point).…”

Photoluminescent, “ice-cream cone” like Cu–In–(Zn)–S/ZnS nanoheterostructures

“…Finally, band gap widening by the entrance of Zn ions into the lattice 72 can take place via diffusion of them into the pre-existed Cu-based seeds. This induces a widening of the band gap, which is quite similar to the doping of Zn into CIS thin films 73 .…”