Study of Covellite (CuS) Single Crystal and Thin Films

In transition metal chalcogenides (TMCs), copper sulphide belonging to IB-VIA group compound semiconductor has wide potential applications. The copper sulphide vary widely in the composition with 0.5 ¿ Cu/S ¿ 2, including numerous non stoichiometric compounds with the formula CuxSy such as CuS2 ¿Villamanitite, CuS-Covellite, Cu9S8 (Cu1.12S) ¿ Yarrowite, Cu39S28 (Cu1.39S) - Spionkopite, Cu8S5 (Cu1.6S)- Geerite, Cu7S4 (Cu1.75S) - Anilite, Cu9S5 (Cu1.8S) - Dignenite, Cu31S16 (Cu1.96S) - Djurleite and Cu2S - Chalcocite. In the copper-deficient compounds, the conduction band minima and valence band maxima are composed of the Cu 4s and S 3p hybridized states and the Cu 3d and S 3p antibonding states, respectively, with holes as the major carrier. While in copper rich compound has a +2 formal valence and 3 antibonding electrons. Of them, covellite CuS is a binary compound having potential application in Lithium ion recharge batteries, gas sensor, photovoltaic application and catalysis. It occurs in the nature as the dark indigo blue mineral. In addition to the technological interest, CuS is an important material from the point of view of fundamental research.