Pentacene self-aggregation at the Au(110)-(1Å~2) surface: growth morphology and interface electronic states

We present an investigation of the growth morphology and electronic properties of pentacene (C22H14) deposited in situ on the (1Å~2)-reconstructed Au(110) surface, in ultra-high-vacuum conditions, at different substrate temperatures. Atomic force microscopy (AFM) investigates evidence of the growth of pentacene in linear stripes preferentially oriented along the [001] direction, on a first thin film phase. Low Energy Electron Diffraction (LEED) data reveal a clear (1Å~3) periodicity induced by the thin film phase, which is stable up to 500 K. The long range periodicity of this 2D ordered phase is improved at higher substrate temperature, due to higher diffusion of the pentacene oligomers, while stripes become more disordered. The electronic properties of the interface are studied by means of high-resolution UV photoelectron spectroscopy, bringing to light the Au–Pentacene interaction electronic levels leading to the formation of the ordered phase.