MBE growth of para-hexaphenyl on GaAs(001)-2×4

Müller, Bert; Kuhlmann, T.; Lischka, K.; Schwer, H.; Resel, Roland; Leising, G.

doi:10.1016/s0039-6028(98)00720-1

Cited by 44 publications

(26 citation statements)

References 29 publications

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“…Previous studies have investigated the growth of molecular films as a function of substrate temperature, finding no evidence of postdeposition processes, probably due to the limited and higher range of substrate temperature explored; nonetheless, an Arrhenius scaling law for the island density has been found. 4,6 The present AFM study demonstrates the occurrence of postnucleation during the growth of molecular thin films by means of organic molecular beam deposition ͑OMBD͒, investigating the film morphology for a wide range of substrate temperatures. Moreover, we obtain an estimate for the activation energy for surface diffusion relative to an archetypal planar molecule onto an amorphous, insulator substrate such as silica.…”

Section: Introductionmentioning

confidence: 80%

“…2 The value of the diffusion coefficient reflects the magnitude of the interaction between the monomer and substrate, which is expected to be very small for molecular materials compared to atomic ones. 3,4 Nucleation and island growth are competing processes, because an arriving monomer can either form a new island with another monomer ͑nucleation͒ or migrate and join an existing island ͑growth͒. The diffusion coefficient determines how large the area is that a deposited monomer ''explores'' in unit time and therefore determines the outcome of the competition between nucleation and growth, controlling the density of stable islands after deposition, given a certain amount of material and a certain deposition rate.…”

Section: Introductionmentioning

confidence: 99%

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Evidence of postdeposition nucleation in organic molecular thin films

et al. 2004

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We analyze the growth of 1-nm-thick films of an organic molecule grown on silica by means of molecular beam deposition. Samples were deposited at a constant rate over a very wide substrate temperature range. By an ex situ atomic force microscopy study two main behaviors are revealed: for samples deposited below 200 K the density of islands is temperature independent and is demonstrated to arise from postnucleation phenomena; above 200 K island density scales with temperature following an Arrhenius law, allowing us to estimate an energy barrier for monomer diffusion of (0.122Ϯ0.011) eV.

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Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Evidence of postdeposition nucleation in organic molecular thin films

et al. 2004

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“…In all cases the Pc films exhibit structures reflecting weakly-interacting molecules with monolayer structures that do not resemble native bulk crystal structures. Other examples of overlayers dominated by overlayer-substrate energy include para-hexaphenyl on GaAs(001), [117] tetrathiafulvalene tetracyanoquinodimethane (TTF-TCNQ) on KCl, [118] protoporphyrins on HOPG, [119] pyridine on heulandite, [120] tetra(4-pyridyl)porphyrin [121] and tetraphenylporphyrin [122] on KCl.…”

Section: Observations Of Molecular Epitaxymentioning

confidence: 99%

Epitaxy and Molecular Organization on Solid Substrates

2001

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The recent emergence of molecular films as candidates for functional electronic materials has prompted numerous investigations of the underlying mechanisms responsible for their structure and formation. This review describes the role of epitaxy in molecular organization on crystalline substrates. A much‐needed grammar of epitaxy is presented that classifies the various modes of epitaxy according to transformation matrices that relate the overlayer lattice to the substrate lattice. The different modes of epitaxy can be organized hierarchically to reflect the balance of overlayer–substrate and molecule–molecule energies. In the case of molecular overlayers, the mismatch of overlayer and substrate symmetries commonly leads to coincident epitaxy in which some of the overlayer lattice points do not reside on substrate lattice points. Analyses of numerous reported epitaxial molecular films reveal that coincidence is quite common even though, based on overlayer–substrate interface energies alone, not as energetically favorable as commensurism. The prevalence of coincidence can be attributed to overlayer elastic constants, associated with molecule–molecule interactions within the overlayer, that are larger than the elastic constants of the overlayer–substrate interface. This condition facilitates prediction of the epitaxial configuration and overlayer structure through simple and comparatively efficient geometric modeling that does not require the input of potential energies, while revealing the role of phase coherence between the overlayer and substrate lattices.

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“…The long molecular axes of all molecules within the unit cell are oriented parallel to each other, whereas adjacent molecular planes are tilted about 66°, which form the typical herringbone structure of PSP. PSP films are very promising for the application in blue organic lightemitting diodes (OLED) [3,6,11] and have been grown previously on different substrates using conventional physical vapor deposition [3,6,11,12] or organic molecular beam epitaxy (OMBE) [13,14]. It was generally shown that the nature of the substrate, substrate temperature and the deposition rate are the determining parameters for molecular packing.…”

Section: Introductionmentioning

confidence: 99%

Organic thin films grown by hot wall epitaxy on inorganic substrates

Sitter¹,

Andreev²,

Teichert

et al. 2005

Physica Status Solidi (b)

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In this work we use Atomic Force Microscopy and X-ray diffraction to study the morphology and thegrowth kinetics of para-sexiphenyl layers deposited by hot wall epitaxy on crystalline mica (001) and KCl (001) substrates. It is shown that para-sexiphenyl forms on mica very long parallel oriented crystalline needles with one preferential direction. In contrast, on KCl (001) the growth is characterized by a coexistence of long needles ("laying" molecules) and terrace structured islands ("standing" molecules). The former belong to the initial growth stage of the films, generating a rectangular network in accordance with the surface symmetry of the substrate.

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MBE growth of para-hexaphenyl on GaAs(001)-2×4

Cited by 44 publications

References 29 publications

Evidence of postdeposition nucleation in organic molecular thin films

Evidence of postdeposition nucleation in organic molecular thin films

Epitaxy and Molecular Organization on Solid Substrates

Organic thin films grown by hot wall epitaxy on inorganic substrates

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