Structural characterization of CuInS₂ thin films from Cu–In metal inks

Abstract

We report the structural characterization of CuInS2 thin films based on Cu–In metal inks. CuInS2 films from the precursor films with different Cu/In ratios were sulfurized and investigated by SEM, XRD, Raman, and XPS. Morphological and compositional changes before and after etching of CuS impurity phase were also compared. By ex situ characterization of the CuInS2 films sulfurized at different temperatures, an established mechanism is proposed to explain the sulfurization process. The sulfurization is a diffusion‐limited process, in which the diffusion rate differences of Cu and In control the intermediate phases. Moreover, the Cu/In ratio and sulfurization temperature determine the morphological and structural qualities of the CuInS2 films.

Synthesis of CuInS2 by Sulfide Ion‐Exchange of CuIn(OH)5 Precursors

“…Stoichiometric CuInS 2 compounds are generally obtained with certain temperature, time, and reagents. 7,[9][10][11][12] However, the current synthetic route was effective for the desired metal stoichiometry with only pH control of the solution.…”

“…With the pH of 8.0, both chloride‐ and nitrate‐based starting materials produced the stoichiometric CuIn(OH) 5 precursor applied to synthesize CuInS 2 compounds via sulfide ion‐exchange. Stoichiometric CuInS 2 compounds are generally obtained with certain temperature, time, and reagents . However, the current synthetic route was effective for the desired metal stoichiometry with only pH control of the solution.…”

“…The annealed CuInS 2 under H 2 /Ar atmosphere had a chalcopyrite phase. 9,15 As shown in Table 3, the lattice parameters of chalcopyrite CuInS 2 from chloride salts were a = 5.528 Å and c = 11.090 Å. Those of CuInS 2 from nitrate salts were a = 5.568 Å and c = 11.060 Å.…”

“…After anion exchange by Na 2 S, CuInS 2 were produced in an amorphous phase. The annealed CuInS 2 under H 2 /Ar atmosphere had a chalcopyrite phase . As shown in Table , the lattice parameters of chalcopyrite CuInS 2 from chloride salts were a = 5.528 Å and c = 11.090 Å.…”