Phases and morphorlogy of CuIn1-xGaxS2 films prepared by chemical co-reduction

Abstract

Ga doping is an important method to regulate the energy structure and photoelectric properties of CuInS2. CuIn1-xGaxS2 films were prepared by using copper nitrate, indium nitrate, gallium nitrate and thioacetamide as raw materials and anhydrous ethanol as the solvent. The effects of reacting time and temperature on the phase composition were studied, and the energy band gaps were calculated and analyzed. Experimental results show that, during the holding time of 5–20 h, the XRD peak intensities of CuIn1-xGaxS2 films were obviously enhanced with the increase of holding time, and the crystallinity became better. When the holding time is 20 h, the crystallinity of CuIn1-xGaxS2 films became better with the increase of reaction temperature between 180 °C and 220 °C. When the reaction temperature exceeded 200 °C, the crystallinity gradually deteriorated. The XRD peaks of CuIn1-xGaxS2 film shifts to the right as the concentration of Ga increased, but it is always between those of CuInS2 and CuGaS2. When the concentration of Ga is 0, the XRD peak of the target product is obviously stronger than other concentrations, and the crystallinity is the best. When the concentration of Ga is more than 0.2, as the concentration of Ga increased, the XRD peak intensities of CuIn1-xGaxS2 film are weak and the crystallinity is deteriorated. The estimated band gap of CuIn1-xGaxS2 film gradually increases with the increase of Ga concentration, but it is always between CuInS2 band gap 1.45 eV and CuGaS2 band gap 2.43 eV.

Keywords

• Chemical co-reduction
• CuIn1-xGaxS2
• Reacting time
• Reacting temperature
• Band gap