Optical and electrical properties of Al:WS₂ films prepared by atomic layer deposition and vulcanization

Composition, structure, optical and electrical properties of Al:WS₂ (un-doped and Al-doped WS₂) films prepared by atomic layer deposition (ALD) and CS₂ vulcanization processing have been studied. Results show that Al:WS₂ films grow with a preferential c-orientation. The core-level binding energies (BEs) of W 4f, S 2p, O 1s and Al 2s decrease with increasing Al doping content, indicating that Al-doped WS₂ films have a p-type conductivity. Optical property analysis shows that the absorption coefficient (∼10⁷ m^-1) is comparable to that of WS₂ single crystals and that Al doping content can tune the optical band gap of the films. Hall measurements show that p-type conductive Al-doped WS₂ films can be obtained by Al doping. Hall mobility values for the un-doped WS₂ and 2.40% Al-doped WS₂ films are 1.63 × 10¹ and 9.71 cm² V^-1 s^-1, respectively. Comparing with un-doped WS₂ films, the comparable Hall mobility of Al-doped WS₂ films can be achieved by appropriate Al doping contents.