Synthesis and Characterization of CuIn(1−x)Ga(x)Se(2) Semiconductor Nanocrystals

In this paper, the synthesis and characterization of CuIn(1−x)Ga(x)Se(2) (0 ≤ x ≤ 1) nanocrystals are reported with the influences of x value on the structural, morphological, and optical properties of the nanocrystals. The X-ray diffraction (XRD) results showed that the nanocrystals were of chalcopyrite structure with particle size in the range of 11.5–17.4 nm. Their lattice constants decreased with increasing Ga content. Thus, the x value of the CuIn(1−x)Ga(x)Se(2) nanocrystals was estimated by Vegard’s law. Transmission electron microscopy (TEM) analysis revealed that the average particle size of the nanocrystals agreed with the results of XRD. Well-defined lattice fringes were shown in the TEM images. An analysis of the absorption spectra indicated that the band gap energy of these CuIn(1−x)Ga(x)Se(2) nanocrystals was tuned from 1.11 to 1.72 eV by varying the x value from 0 to 1. The Raman spectra indicated that the A(1) optical vibrational mode of the nanocrystals gradually shifted to higher wavenumber with increasing x value. A simple theoretical equation for the A(1) mode frequency was proposed. The plot of this equation showed the same trend as the experimental data.