Deposition by radio frequency magnetron sputtering of GaV4S8 thin films for resistive random access memory application

Abstract

We report here on the deposition of GaV4S8 thin layers by radio frequency (RF) magnetron sputtering in pure argon using a GaV4S8 target synthesized by spark plasma sintering. Thin layers were deposited at low deposition pressure and RF power, respectively 5.33 Pa and 60 W (i.e. 3 W cm−2). Since as-deposited thin layers were sulfur-poor and amorphous, a one hour ex-situ annealing at 873 K in a sulfur-rich atmosphere was performed to restore the stoichiometric composition GaV4S8 and the expected crystalline structure. Chemical analyses and high resolution transmission electron microscopy observations of thin layers are consistent with a GaV4S8 phase without any secondary phase. Rietveld refinements of the X-ray diffraction (XRD) patterns confirm the good crystalline quality of the annealed deposited film constituted of crystallites exhibiting an average grain size in the 32–36 nm range. Moreover, an excellent agreement was obtained between Rietveld refinement performed on GaV4S8 powder and thin films XRD data.