Optical and structural properties of Ag(Cu)-As2Se3 chalcogenide films prepared by a photodoping

We prepared Ag(Cu)-As2Se3 films by step-by-step photodoping Ag (or Cu) into an evaporated As2Se3 film and determined their optical properties such as refractive index and band gap energy from the transmission spectrum of the sample. The highest concentration of the metal doped into the amorphous As2Se3 film was 21 at.% for Ag and 7at.% for Cu. Moreover we performed Raman spectroscopy to obtain information about the local structure of the photodoped chalcogenide films. It has been found that there is a distinct difference in the optical properties between Ag-As2Se3 and Cu-As2Se3 films. The measured Raman spectra agree approximately with ones we previously obtained for bulk glasses. In our case, this agreement means that the successive photodoping used here produces nearly homogeneous chalcogenide films. It has also been found that a mixture of Se clusters (Se-8 ring, Se-12 ring, and Se4 chain) is formed near the surface of the photodoped Ag(Cu)-As2Se3 films. (C) 2004 Elsevier B.V. All rights reserved.