Characterisation of metal-organic semiconductor interfaces: In and Sn on CuPc

Abstract
We present an investigation of the chemistry and electronic structure formation during the development of the interfaces between In or Sn and thin films of archetypal organic molecular solid, CuPc (copper phthalocyanine) in ultra high vacuum (UHV) conditions. The photoemission measurements were performed by means of high-resolution photoemission electron spectroscopy (HR-PES), core-level (CL) and valence-band (VB), and using synchrotron-radiation (SR) facility. At room temperature the two stages of the In/CuPc interface formation upon metal deposition are observed. On the first one In atoms penetrate into organic film, modify it's doping, show obvious chemical interaction with CuPc. The site positions of In ions diffused into the CuPc film are derived to be close to the pyrolle nitrogens of copper phthalocyanine. This stage stops at a stoichiometry of In₂CuPc. At higher level of indium deposition the metallic film formation on the top of organic film takes place (second stage). The electronic structure of the interface, which forms during Sn deposition onto CuPc thin films, shows both similarity and difference as compare to indium.