Preparation and optical properties of AgGaS 2 nanofilms

In this paper, AgGaS 2 nanofilms have been prepared by a two‐step process involving the successive ionic layer absorption and reaction (SILAR) and annealing method. Using AgNO 3 , GaCl 3 and Na 2 S 2 O 3 as reaction sources, the mixture films were firstly deposited on quartz glass substrates at room temperature, and then annealed in Ar environment at 200–500 °C for 4 h, respectively. The effects of annealing temperature on structural and optical properties were investigated by XRD, UV‐Vis, EDS and photoluminescence (PL) spectra. It was revealed in XRD results that α‐Ag 9 GaS 6 was contained in the samples annealed at 200 °C, and this phase was decreased with increase of the annealing temperatures. When the sample was annealed at above 400 °C, the chalcopyrite AgGaS 2 nanofilm was obtained. The preferred orientation was exhibited along the (112) plane. It was shown in atomic force microscopy (AFM) results that the grain sizes in AgGaS 2 nanofilms were 18‐24 nm and the thin films were smooth and strongly adherent to the substrates. When the annealing temperature was higher than 400 °C, it is an optimum condition to improve the structural and optical properties of the AgGaS 2 thin films. The room temperature PL spectra of AgGaS 2 nanofilms showed prominent band edge emission at 2.72 eV. Based on all results mentioned above, it can be concluded that the SILAR‐annealing method is preferable to preparing high‐quality AgGaS 2 nanofilms. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)