Ordering of organic molecules on passivated reactive substrates: PTCDA on O-p(2×2)–Ni()

Tiba, M.V.; Kurnosikov, O Oleg; Flipse, C. F. J.; Koopmans, B.; Swagten, H.J.M.; Jonge, W. J. M. de

doi:10.1016/s0039-6028(01)01682-x

Cited by 16 publications

(14 citation statements)

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Section: Introductionmentioning

confidence: 97%

“…[8][9][10][11] For this class of substrates it has been shown though that bonding to the substrate and hence the molecular order can be influenced by changing the type of the molecule or by passivating the substrate. 8,12,13 An example of a stable interface is that of C 60 /Ni͑110͒, 14,15 with a decomposition temperature of C 60 around 850 K. A strong interaction has been reported in the latter case as well.In this paper we present the structural and electronic properties of the interface between pentacene and Co. Pentacene is one of the semiconducting organic materials with a high charge carrier mobility. [16][17][18][19][20] For the structural properties of this particular interface, we will show that pentacene forms ordered domains when deposited at elevated temperatures on polycrystalline Co films, with an almost perpendicular orientation of the molecules to the substrate.…”

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confidence: 96%

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Morphology and electronic properties of the pentacene on cobalt interface

Tiba

Jonge

Koopmans

et al. 2006

Journal of Applied Physics

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In this paper, we report the structural and electronic properties of pentacene thin films grown on a polycrystalline Co film using atomic force microscopy and ultraviolet photoemission spectroscopy ͑UPS͒, respectively. Investigation of this type of interface is of importance for the engineering of hybrid organometallic spintronic devices for which the use of spin polarized electrodes is a prerequisite. Uniform single crystalline areas of pentacene as large as several micrometers, with molecules arranging almost perpendicular to the substrate, were obtained. For the electronic properties at this interface, we have found an energy barrier for the hole injection of about 1 eV, in spite of the fact that the ionization potential of pentacene reported previously equals the work function of Co. A shift of the vacuum level of the same magnitude has also been observed. A comparison of the UPS spectra of the pentacene films with the gas phase spectrum directly indicates that hybridization effects are present at this interface. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2363707͔ INTRODUCTIONMolecular organic semiconductors have become a very active area of research during the past decade. The structural flexibility due to weak intermolecular bonds and the endless possibilities for chemical synthesis of new molecules give molecular systems a unique advantage over inorganic semiconductors for relatively simple fabrication of ͑opto-͒ electronic devices such as light emitting diodes for flexible or even transparent displays, transistors, solar cells, sensors, and solid state lasers. Applications into electronic devices in which the spin degree of freedom of the electron is exploited ͑spintronics͒ have recently started to be considered, motivated by the notion that organic semiconductors are materials with large spin relaxation times. [1][2][3][4][5] Spin valves with a significant magnetoresistance have been produced with Alq 3 thin films sandwiched between two ferromagnetic electrodes. 4,5 In response to the technological success of the organic semiconductors, fundamental research, with the goal of understanding the surface and interface properties of these systems, has followed. Such studies have proven to be valuable for device engineering, as well as from the fundamental viewpoint, electronic properties of interfaces between organic semiconductors and metals being still puzzling for scientists. While the electronic and structural properties of large organic molecules on noble metals and semiconducting or semimetallic substrates have been extensively studied, only a limited number of studies on more reactive substrates, such as the ferromagnetic transition metals, have been reported. 6 Such investigations are of crucial relevance to understand and control efficient spin injection from ferromagnetic electrodes into organic thin films.In the ferromagnetic transition metals, both the magnetic behavior and the reactivity originate from the high density of the d states near the Fermi level. For the structural propertie...

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Section: Introductionmentioning

confidence: 97%

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confidence: 96%

Morphology and electronic properties of the pentacene on cobalt interface

Tiba

Jonge

Koopmans

et al. 2006

Journal of Applied Physics

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“…Perhaps the most popular case is Si, where the native oxide layer is removed by dipping the samples in HF, and the dangling bonds are saturated with H. Another example is Ni(111), a ferromagnetic surface, which is passivated by a monolayer of oxygen. [121] Many other substrates mostly dedicated to the study of the films, rather than to their applications, include alkali halides, glass, quartz, and the 2D HOPG, mica, and metal dichalcogenides.…”

Section: The Choice Of Substratesmentioning

confidence: 99%

Perspectives on Thin Molecular Organic Films

Fraxedas¹

2002

Adv. Mater.

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The engineering versatility of molecular organic materials, together with their attractive electronic, magnetic, and optical properties, have triggered their preparation as thin films in the last years. Although the interactions between molecules and inorganic substrates are rather weak (van der Waals, hydrogen bonding, etc.), the crystallographic phase, the type and degree of orientation, and the morphology of the resulting films critically depend on the interface and the kinetics of growth. The control of the structure and morphology of the films is thus essential when envisioning practical applications. The relevance of interfaces in the growth and doping of films is discussed, and the phenomenology of polymorphism is explored. Additional issues such as the mechanical properties are also addressed. The figure, showing a scanning tunneling microscopy image of a monolayer of bis(ethylenedithio)‐tetrathiafulvalene on a Au(111) substrate, illustrates the interface issue.

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“…It is therefore not surprising that extensive studies of the growth of perylene on metal substrates have been carried out using various methods [5][6][7][8][9]. Also STM was widely applied for a real space analysis of layers of perylene and its planar derivatives (PTCDA, PTCDI and DMe-PTCDI) on a number of substrates, single crystals of: Ag [10][11][12][13], Au [14][15][16], HOPG [17,18], MoS 2 [17], Ni [19], Cu [20], GaAs [21]. Such studies yield information on the structure of organic layers including local features (submolecular resolution and tunnelling spectroscopy).…”

Section: Introductionmentioning

confidence: 99%