Growth, optical and structural characterization of layered GaS films prepared by reactive RF sputtering method

Good-crystallinity gallium sulfide (GaS) films were prepared on silica glass substrates by RF reactive magnetron sputtering with an Ar and H(2) gas mixture with various hydrogen fractions (H(mf) = 0.1-0.4). The structure and optical properties of the sputtered GaS films were studied. The X-ray diffraction measurements showed that GaS films deposited at 500 degrees C using Ar as the sputtering gas (H(mf) = 0) had amorphous structures, while those using H(mf) = 0.4 had polycrystalline structures with the c-axis perpendicular to the substrate plane. The absorption edges of the polycrystalline GaS films showed a direct allowed transition with an optical gap of E(og) = 3.0eV, which was in good agreement with those measured in single-crystal GaS by previous researchers.