Structural and optical characterization of single-phase Culn(Se,S)_2 thin films deposited using a two-step process

摘要

CuInSe_2 has a band gap of about 1.0 eV, which limits the conversion efficiency of complete CuInSe_2/CdS/ZnO devices. In order to increase the conversion efficiency of devices, it is necessary to increase the band gap value of the absorber films to about 1.2 eV. This can be achieved by systematically substituting some indium with a group III element and/or selenium with another group VI elements. The substitution of In and/or Se results in a shrinkage of the lattice parameters and thus an increase in the band gap value of the absorber films. However, this process is extremely complicated, especially for conventional two-step growth processes in which metallic alloys are exposed to Se and/or S species. In this contribution, the optical and structural properties of homogeneous single-phase CuIn(Se,S)_2 alloys are demonstrated for the novel two-step deposition process.