Modification of GaAs(100) surfaces upon adsorption of perylene derivatives

Salvan, Georgeta; Silaghi, Simona D.; Paez, B. A.; Kampen, Thorsten U.; Zahn, Dietrich R. T.

doi:10.1016/j.apsusc.2004.05.058

Cited by 6 publications

(7 citation statements)

References 15 publications

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“…However, infrared spectroscopy and X-ray diffraction techniques indicate a preferential orientation with the PTCDA molecules lying flat on the passivated Si and GaAs substrates [6,22]. Furthermore, the spectral signature of PTCDA MLs is conform with a flat orientation of molecules on the passivated substrate, while the suppression of the symmetric C¼O stretching in DiMe-PTCDI spectra supports a molecular tilting [23]. Thus the replacement of the anhydride oxygen with the methyl-imide group in DiMe-PTCDI is responsible for the dramatic difference in molecular orientation.…”

Section: Article In Pressmentioning

confidence: 86%

Structural and morphological properties of N,N′-dimethyl-3,4,9,10-perylenetetracarboxylic diimide films on passivated GaAs(100) substrates

Salvan

Silaghi

Paez

et al. 2005

Journal of Crystal Growth

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Section: Article In Pressmentioning

confidence: 86%

Structural and morphological properties of N,N′-dimethyl-3,4,9,10-perylenetetracarboxylic diimide films on passivated GaAs(100) substrates

Salvan

Silaghi

Paez

et al. 2005

Journal of Crystal Growth

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“…3, and for PTCDA, PTCDI, and Me-PTCDI, the mode frequencies and Huang-Rhys factors are compatible with observed resonant Raman cross sections. [41][42][43][44] …”

Section: Vibronic Coupling Constants and Huang-rhys Factors For Inmentioning

confidence: 99%

Crystallochromy of perylene pigments: Interference between Frenkel excitons and charge-transfer states

2009

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The optical properties of perylene-based pigments are arising from the interplay between neutral molecular excitations and charge transfer between adjacent molecules. In the crystalline phase, these excitations are coupled via electron and hole transfer, two quantities relating directly to the width of the conduction and valence band in the crystalline phase. Based on the crystal structure determined by x-ray diffraction, densityfunctional theory ͑DFT͒ and Hartree-Fock are used for the calculation of the electronic states of a dimer of stacked molecules. The resulting transfer parameters for electron and hole are used in an exciton model for the coupling between Frenkel excitons and charge-transfer states. The deformation of the positively or negatively charged molecular ions with respect to the neutral ground state is calculated with DFT and the geometry in the optically excited state is deduced from time-dependent DFT and constrained DFT. All of these deformations are interpreted in terms of the elongation of an effective internal vibration which is used subsequently in the exciton model for the crystalline phase. A comparison between the calculated dielectric function and the observed optical spectra allows to deduce the relative energetic position of Frenkel excitons and the chargetransfer state involving stack neighbors, a key parameter for various electronic and optoelectronic device applications. For five out of six perylene pigments studied in the present work, this exciton model results in excellent agreement between calculated and observed optical properties.

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“…The increase of the Raman signal of the organic layer upon metal deposition was also observed for In and Ag [7]. This effect occurs due to the enhancement of the electric field of the incoming and scattered radiation induced by plasmons that are resonantly excited by the electromagnetic radiation in the metal clusters.…”

Section: Methodsmentioning

confidence: 62%

“…3 Results and discussion The activation of modes with lower symmetry was also observed during the deposition of other metals, like Ag and In onto DiMePTCDI [7]. This is a well know effect for molecules in contact with metal surfaces [13].…”

Section: Methodsmentioning

confidence: 79%

“…Thus the vibrational spectrum is a characteristic fingerprint of the investigated system. Information concerning the chemical identity, charge states, processes at interfaces and structural order in organic materials, can be identified using this spectroscopic technique [7,8,9,10]. Here, the chemical aspects of the interface formation between magnesium and a molecule from the class of the perylene derivatives, namely N,N'-DiMethyl-3,4,9,10-Perylene Tetra Carboxylic DiImide (DiMePTCDI) is investigated.…”

Section: Introductionmentioning

confidence: 99%

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Interface formation of Mg with DiMePTCDI studied by Raman spectroscopy

Paez

Salvan

Scholz

et al. 2005

phys. stat. sol. (c)

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PACS 68.35.Ja, 78.30.Jw Metal/organic interfaces play an important role in the performance of organic based devices. In this work the interface formation between Mg and N,N'-DiMethyl-3,4,9,10-Perylene Tetra Carboxylic DiImide (DiMePTCDI) films grown on sulphur-passivated GaAs (100) substrates is investigated in situ by Raman spectroscopy. The Raman spectra are taken in a backscattering geometry at room temperature under resonance conditions with the 488 nm (2.54 eV) Ar + laser line. They reveal that when Mg is deposited onto a 15 nm DiMePTCDI layer the external phonon modes are preserved up to large metal coverages. Since these modes are a fingerprint of the molecular crystal, their preservation indicates a low diffusion of Mg into the DiMePTCDI layer. Concerning the internal molecular modes, the Mg deposition induces a breakdown of selection rules which is proposed to originate from a dynamical charge transfer between the DiMePTCDI molecules and the metal. Above 0.3 nm nominal thickness of Mg the line-shape of the molecular breathing mode at 221 cm -1 develops an asymmetric tail towards higher frequencies. A similar effect is observed for the bands that occur at 1291 cm -1 and 1606 cm -1 but the asymmetry appears at the low frequency side. This line-shape asymmetry is likely to be related to a Fano resonant coupling between the molecular vibrational modes and the electronic continuum of states of metallic clusters formed above 0.3 nm Mg coverage.

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Modification of GaAs(100) surfaces upon adsorption of perylene derivatives

Cited by 6 publications

References 15 publications

Structural and morphological properties of N,N′-dimethyl-3,4,9,10-perylenetetracarboxylic diimide films on passivated GaAs(100) substrates

Structural and morphological properties of N,N′-dimethyl-3,4,9,10-perylenetetracarboxylic diimide films on passivated GaAs(100) substrates

Crystallochromy of perylene pigments: Interference between Frenkel excitons and charge-transfer states

Interface formation of Mg with DiMePTCDI studied by Raman spectroscopy

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