Morphology Change of C₆₀ Islands on Organic Crystals Observed by Atomic Force Microscopy

Abstract

Organic-organic heterojunctions are nowadays highly regarded materials for lightemitting diodes, field-effect transistors, and photovoltaic cells with the prospect of designing low-cost, flexible, and efficient electronic devices. 1-3 However, the key parameter of optimized heterojunctions relies on the choice of the molecular compounds as well as on the morphology of the organic-organic interface 4 which thus requires fundamental studies. In this work, we investigated the deposition of C 60 molecules at room temperature on an organic layer compound, the salt bis(benzylammonium)bis(oxalato)-cupurate(II), by means of non-contact atomic force microscopy (nc-AFM). Threedimensional molecular islands of C 60 having either triangular or hexagonal shapes are formed on the substrate following a "Volmer-Weber" type of growth. We demonstrate the dynamical reshaping of those C 60 nano-structures under the local action of the AFM tip at room temperature. The dissipated energy is about 75 meV and can be interpreted as the activation energy required for this migration process.1

Influence of electrospray deposition on C60 molecular assemblies

“…The ease of its thermal evaporation, the organised structure generally obtained, and the potential of its uses have made C 60 a model case for on-surface molecular studies [19][20][21][22][23][24][25][26][27]. Two-dimensional C 60 layers have been observed on metals [20,25,28] and metal oxide semiconductors [23,24], while large three-dimensional molecular islands or clusters have been revealed on ionic crystals or bulk insulators [22,26,27,29]. Most of the studies have been performed after thermal evaporation (TE) of C 60 from a crucible, but C 60 is also one of the first molecules studied in HV-ESD experiments [5,30].…”

Toward Characterization of a Rectangular Groove on a Metallic Surface by Multi-Angle Light Scattering

“…A natural approach to evaluate the surface quality is based on the physical sizes of surface defects. Three-dimensional surface profiles of defects can be obtained utilizing state-of-the-art instruments, such as white light interferometry [1], [2] and atomic force microscopy [3], [4], with which surface quality can be evaluated reliably. However, the measurements suffer from low efficiency, which hinders their applications in highvolume quality control.…”

Towards surface diffusion potential mapping on atomic length scale

“…In the absence of structural changes on the tip, contrast in the damping channel can be associated with atomic dynamic processes on the surface which lead to energy dissipation. For example, it has been shown recently that diffusion energy barriers can be estimated from the force sensor's dissipated energy when reshaping C 60 nanostructures 32 . The relation between tip stimulated diffusion and the energy dissipation has also been discussed in the case of Si adatoms on Si(111) 33 .…”