In this paper we study the growth of Cu x Se y and Na x Cu y Se z thin films on polycrystalline Cu substrates. The investigation took place in situ by means of photoemission spectroscopy with synchrotron radiation, in UHV. Deposition of elemental Se with a dense flux on a polycrystalline Cu substrate at RT and subsequent heating to 100°C causes the formation of a thick Cu 2-x Se film (with x equal or very close to zero). A phase transition of this copper selenide occurs by annealing at 200°C. Deposited Na on the Cu 2-x Se film is diffused into the bulk, resulting in the formation of a Na x Cu y Se z compound. Exposure to Cl 2 at 120°C causes the out-diffusion of Na to the surface, where NaCl is formed. The Na diffusion in and out of the copper selenide film is analogous to alkali intercalation–deintercalation from TX 2 layer compounds.
Systematic Study on Electronic Structure of Organic Thin Films and Interfaces by Photoemission Spectroscopy with Synchrotron Radiation
