(001)-oriented Cu2-ySe thin films with tunable thermoelectric performances grown by pulsed laser deposition

Highly (001)-oriented Cu2-ySe thin films with tunable thermoelectric performances have been grown by pulsed laser deposition. By using targets with different Cu/Se ratios that further determines the copper deficiency of as-grown films, the carrier concentrations of as-grown films are tuned within a broad range from 1018 to 1021 cm−3. The optimum performance is observed at carrier concentration ~1.58×1020 cm−3. The distinct properties of Cu2-ySe thin films with nearly ideal chemical stoichiometric ratio are observed. In addition, a weak change in the electrical transport during the second-order phase transition was observed in the thin films due to the anisotropic structure of the Cu2-ySe.