The Growth of CuGaTe₂ Thin Films by Two-Step Closed Space Sublimation

CuGaTe₂ layers are successfully grown on Si (001) and Mo/quartz substrates using two-step closed space sublimation (CSS). The surface morphology of the Cu₂Te first layer is affected by the surface free energy of the different substrates. Cu₂Te grown on Si (001) comprises hexagonal islands which are highly oriented to the (0001). Conversely, Cu₂Te layers formed on Mo/quartz substrates forms a thin film. The surface morphology and the quality of the crystals in the CuGaTe₂ layers are investigated. Overgrowth by CuGaTe₂ of the Cu₂Te islands on Si substrates is confined to the islands only and there is no nucleation on the bare substrate. On the contrary, overgrowth by CuGaTe₂ on the continuous Cu₂Te films on Mo/quartz substrates produces continuous thin films. Therefore, the surface morphology of the CuGaTe₂ layers can be controlled by changing the substrate material because they have different surface free energies.