Growth morphology and electronic structure of 2D ordered pentacene on the Au(1 1 0)-(1Å~2) surface

High-quality ordered growth and characterization of organic systems is an important requirement to understand the physical properties underlying the new organic-molecule based electronic devices. In this work, pentacene (C22H14) is ultra-high-vacuum deposited in situ on the (1Å~2)-reconstructed surface of Au(1 1 0), at different substrate temperatures. Low-energy electron diffraction reveals a two-dimensional (2D) ordered phase, showing the presence of a (1Å~3) pentacene-induced long-range periodicity, for room-temperature deposition. High-resolution UV photoelectron spectroscopy investigations for pentacene adsorption at room- and low- (80 K) temperature, bring to light the new interface electronic levels and the molecular orbital evolution. Higher substrate temperature (370 K) during adsorption induces higher pentacene mobility, thus improving long-range ordering. Atomic force microscopy images at higher coverage show the presence of pentacene stripes, grown on top of the first 2D ordered layer, with a preferred orientation perpendicular to the substrate [1 -1 0] direction.