Abstract
WS x films were sputter-deposited on Si, SiO 2/Si, and glass substrates from a WS 2 target in an Ar/H 2S atmosphere. Their structure, morphology, chemical composition, and electrical properties were investigated as a function of deposition parameters such as working pressure and H 2S fraction. Films could be grown in the composition range WS 0.3−WS 3.5. Crystallisation was achieved at substrate temperatures T s > 70 ° C and compositions 0.7 ≤ x ≤ 1.95. While the first 5–50 nm near the interface exhibited a basal orientation ( c⊥), further growth resulted in the formation of edge-oriented platelets ( c∥) giving rise to a porous, lamellar microstructure. The crystalline structure was mainly turbostratic, while some degree of ordered stacking was present in samples grown at high substrate temperature (600 °C). Resistivity measurements showed a semiconductor-type temperature dependence characterised by activation energies up to 95 meV. Sheet resistance was found to be nearly independent of film thickness, suggesting that the main carrier transport takes place in an interfacial layer of about 20 nm in thickness.
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