Phase identification of RF-sputtered SnS thin films using rietveld analysis of X-ray diffraction patterns

Tin monosulfide (SnS) is a promising material for a photovoltaic absorber layer. Significant strides have been taken to better understand its material properties. The X-ray diffraction patterns of radio-frequency sputtered SnS thin films are investigated. Samples were deposited under varying total pressure, target power, substrate-to-target distance, and substrate temperature. Rietveld refinement of samples deposited under varying conditions yielded evidence of multiple phases present in SnS thin films. Refinements were completed with one or more tin sulfide phases, showing a dominant herzenbergite SnS phase (Pbnm). Possible secondary phases include orthrhombic (Cmcm) and cubic (Fm3m) crystal structures. Lattice parameters, cell volume, and unit cell density were investigated as a function of deposition conditions. Results indicate that growth mode is related to deposition rate. Early studies of heated stage depositions showed that SnS thin films have added mobility at the substrate.