Structure and electrical properties of sputtered Cu2−xTe films (0 ≤ x ≤ 1)

Highlights: • Cu_2−xTe films sputtered from targets made of Cu and Te powders for the first time. • Dominant crystalline phases were obtained depending on growth parameters. • Simple and robust method for Cu_2−xTe film growth and phase control is provided. • Electrical properties vary significantly depending on Cu_2−xTe crystalline phase. - Abstract: Radio frequency sputtering was used to grow copper telluride films from targets fabricated by cold pressing mixtures of copper and tellurium powders. Through this method, Cu_2−xTe targets and films with 0 ≤ x ≤ 1 in nominal composition were elaborated. X-ray diffraction showed that the films comprised mixtures of various copper telluride phases. However, dominant phases resulted, in most cases, depending on the target nominal composition and on the substrate temperature. The temperatures employed varied between room temperature and 350 °C. In the specific cases of growths at 100 °C from the target with nominal composition [Cu]/[Te] = 1, and at 200 °C from the [Cu]/[Te] = 1.5 target, nearly single phases of CuTe and Cu₇Te₅ were obtained, respectively. Through Hall effect measurements the resistivity, free carrier density and mobility were determined as a function of target composition and substrate temperature.