Ehrlich-Schwoebel effect for organic molecules: Direct calculation of the step-edge barrier using empirical potentials

Fendrich, M.; Krug, Joachim

doi:10.1103/physrevb.76.121302

Cited by 33 publications

(25 citation statements)

References 22 publications

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“…The capability of empirical potentials has been shown for several molecular systems. [31][32][33][34] In particular, similar calculations could elucidate the experimental data for a very similar system, PTCDA on KCl͑001͒. 16 The minimization of the electrostatic energy is assumed to be responsible for the ordering in other systems of organic molecules with strong partial charges on alkali halide substrates.…”

Section: Calculationsmentioning

confidence: 97%

N , N ′ -dimethylperylene-3,4,9,10-bis(dicarboximide) on alkali halide (001) surfaces

Fendrich

Lange

Weiss

et al. 2009

Journal of Applied Physics

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The growth of N,N′-dimethylperylene-3,4,9,10-bis(dicarboximide) (DiMe-PTCDI) on KBr(001) and NaCl(001) surfaces has been studied. Experimental results have been achieved using frequency modulation atomic force microscopy at room temperature under ultrahigh vacuum conditions. On both substrates, DiMe-PTCDI forms molecular wires with a width of 10nm, typically, and a length of up to 600nm at low coverages. All wires grow along either the [110] direction (or [11¯0] direction, respectively) of the alkali halide (001) substrates. There is no wetting layer of molecules: atomic resolution of the substrates can be achieved between the wires. The wires are mobile on KBr but substantially more stable on NaCl. A p(2×2) superstructure in a brickwall arrangement on the ionic crystal surfaces is proposed based on electrostatic considerations. Calculations and Monte Carlo simulations using empirical potentials reveal possible growth mechanisms for molecules within the first layer for both substrates, also showing a significantly higher binding energy for NaCl(001). For KBr, the p(2×2) superstructure is confirmed by the simulations; for NaCl, a less dense, incommensurate superstructure is predicted.

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Section: Calculationsmentioning

confidence: 97%

N , N ′ -dimethylperylene-3,4,9,10-bis(dicarboximide) on alkali halide (001) surfaces

Fendrich

Lange

Weiss

et al. 2009

Journal of Applied Physics

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“…Such high barriers are not uncommon for organic systems. Fendrich et al report 0.78 eV for the Ehrlich-Schwoebel barrier of flat lying 3,4,9,10-perylene-tetracaboxylic-dianhydride (PTCDA) on PTCDA(102) using empirical potentials and the nudged elastic band method [132]. For both systems-6P and PTCDA-the calculated diffusion barrier on the terraces is smaller by at least one order of magnitude.…”

Section: Mound Formationmentioning

confidence: 99%

Nucleation and growth of thin films of rod-like conjugated molecules

Hlawacek

Teichert

2013

J. Phys.: Condens. Matter

107

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Abstract. Thin films formed from small molecules rapidly gain importance in different technological fields. To explain their growth, methods developed for zero-dimensional atoms as the film forming particles are applied. However, in organic thin film growth the dimensionality of the building blocks comes into play. Using the special case of the model molecule para-Sexiphenyl, we will emphasize the challenges that arise from the anisotropic and one-dimensional nature of building blocks. Differences or common features with other rodlike molecules will be discussed. The typical morphologies encountered for this group of molecules and the relevant growth modes will be investigated. Special attention is given to the transition between flat lying and upright orientation of the building blocks during nucleation. We will further discuss methods to control the molecular orientation and describe the involved diffusion processes qualitatively and quantitatively.

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“…[23][24][25][26][27][28] In spite of the previously mentioned complexities, the general theory of crystal growth can still be applied to organic film growth after appropriate revision. [3][4][5][6][29][30][31][32] Its adaption to organic systems is an ongoing project, requiring input from carefully chosen experiments that help to single out the special features of ordering and growth at the organic/metal interface. We have chosen Tc/Ag(111) as a suitable model system because tetracene is a representative of the class of polycyclic π -conjugated platelet molecules.…”

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confidence: 99%

Structure and growth of tetracene on Ag(111)

et al. 2011

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The structure of the tetracene/Ag(111) interface in the coverage range θ = 0 to 2.4 ML is studied with scanning tunneling microscopy (STM) at 8 K and with low energy electron diffraction (LEED) at T = 300 . . . 100 K. For θ 0.01 ML, one-dimensional (1D) diffusion of single molecules along 011 -directions is observed even at 8 K. For 0.1 ML < θ < 0.5 ML molecules are homogeneously distributed over the surface forming a disordered phase (static at T = 8 K, dynamic at T = 25 K), indicating a repulsive intermolecular interaction (δ-phase). For θ 0.5 ML, local ordering in the commensurate γ -phase is observed. Further increase of the coverage yields a compressed monolayer (ML) phase (θ ≡ 1 ML) with point-on-line registry (α-phase). The interaction between molecules has been calculated with the force-field approach to rationalize the molecular packing motifs in the various phases. Under most circumstances molecule-molecule interactions are repulsive, in agreement with experimental findings. A simulation of the adsorption up to θ = 1 ML according to the random sequential adsorption (RSA) algorithm shows that the disorder-to-order transition from the δ-to γ -phase occurs close to random close packing (RCP), θ = 0.5-0.6 ML. Since tetracene molecules are a two-dimensional (2D) representation of Onsager's hard rod model, this suggests that this phase transition is driven both energetically and entropically. For θ ≈ 2.23 ML a metastable bilayer phase with point-on-line coincidence is observed (β-phase). The basic structural unit of this phase is a triplet of molecules that are tilted along the long molecular axis against each other; at least one of these molecules is tilted out of the surface plane. Within the β-phase a superstructure of alternating rotation domains is observed. This superstructure has a period of 7.4 nm. The molecular packing in the β-phase resembles the packing in the bulk crystal structure of tetracene, its formation can therefore be interpreted as incipient pseudomorphic growth of tetracene on Ag(111). However, pseudomorphic growth cannot be continued beyond the β-phase.

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Ehrlich-Schwoebel effect for organic molecules: Direct calculation of the step-edge barrier using empirical potentials

Cited by 33 publications

References 22 publications

N , N ′ -dimethylperylene-3,4,9,10-bis(dicarboximide) on alkali halide (001) surfaces

N , N ′ -dimethylperylene-3,4,9,10-bis(dicarboximide) on alkali halide (001) surfaces

Nucleation and growth of thin films of rod-like conjugated molecules

Structure and growth of tetracene on Ag(111)

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