Electronic structure of α-sexithiophene ultrathin films grown on

Ohno, Shinya; Tanaka, Hiroya; Tanaka, Kazuma; Takahashi, Kazutoshi; Tanaka, Masatoshi

doi:10.1039/c7cp05222g

Cited by 8 publications

(6 citation statements)

References 55 publications

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“…In general, this surface is expected to be less reactive as compared to Ag(111) [39]. It is then not surprising that it allows the growth of ordered overlayers such as, for instance, organic architectures [50,51] which are otherwise rarely observed on bare Si surfaces. When π-conjugated molecules are adsorbed the S 1 surface state is generally preserved, and the energy shift which is observed can be explained by charge transfer to or from the overlayer [52].…”

Section: Discussionmentioning

confidence: 99%

Unoccupied electronic states of 2D Si on Ag- 3 -Si(111)

Mrezguia¹,

Giovanelli²,

Ksari³

et al. 2021

J. Phys.: Condens. Matter

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Optimizing substrate characterization to grow 2D Si layers on surfaces is a major issue toward the development of synthesis techniques of the promising silicene. We have used inverse photoemission spectroscopy (IPES) to study the electronic band structure of an ordered 2D Si layer on the 3 × 3 -Ag/Si(111) surface ( 3 -Ag). Exploiting the large upwards band bending of the 3 -Ag substrate, we could investigate the evolution of the unoccupied surface and interface states in most of the Si band gap. In particular, the k ∥-dispersion of the 3 -Ag free-electron-like S 1 surface state measured by IPES, is reported for the first time. Upon deposition of ∼1 ML Si on 3 -Ag maintained at ∼200 °C, the interface undergoes a metal-insulator transition with the complete disappearance of the S 1 state. The latter is replaced by a higher-lying state U 0 with a minimum at 1.0 eV above E F. The origin of this new state is discussed in terms of various Si 2D structures including silicene.

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Section: Discussionmentioning

confidence: 99%

Unoccupied electronic states of 2D Si on Ag- 3 -Si(111)

Mrezguia¹,

Giovanelli²,

Ksari³

et al. 2021

J. Phys.: Condens. Matter

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“…The peak assignment follows previous studies. 46 The three peaks at around 2−4 eV are the antibonding π a states. These orbitals are delocalized over the carbon backbone of the molecule, with negligible sulfur contribution.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The molecular band is already clear at 0.5 ML and both coverages show well-resolved features, as expected for an ordered film and allowing a clear identification of orbital contributions to the density of states (DOS). The peak assignment follows previous studies . The three peaks at around 2–4 eV are the antibonding π a states.…”

Section: Resultsmentioning

confidence: 99%

Spinterface Formation at α-Sexithiophene/Ferromagnetic Conducting Oxide

et al. 2021

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The inorganic/molecular spinterface is an ideal platform for generating extraordinary spin effects. Understanding and controlling these spin-related effects is mandatory for the exploitation of such interfaces in devices. For this purpose we have investigated the adsorption of α-sexithiophene (α-6T) on La 0.7 Sr 0.3 MnO 3 (LSMO) as one of the prototypical material combinations used in organic spintronic devices. Atomic force microscopy (AFM), confocal photoluminescence, X-ray and utraviolet photoelectron spectroscopy, and metastable de-excitation spectroscopy unraveled the structure and the electronic configuration of 6T for various surface coverages. This data set allowed the determination of the characteristic features of occupied states: the band diagram and the work function. Finally, density functional theory enabled us to establish that the spin polarization in 6T molecular orbitals critically depends on the termination layer of LSMO, showing a substantial effect on the MnO-terminated one only. We believe that this research provides important hints for a comprehensive understanding of spinterface effects in general and offers key suggestions for the optimization of 6T/LSMO-based spin devices through the engineering of LSMO termination layer.

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“…There are a couple of photoelectron spectroscopy studies of 6 T thin films on (modified) Si surfaces [35][36][37][38]. However no UPS data of 6 T on the HF-treated surface of Si(100) is available and it remains an open question whether the passivation is sufficient for electronic decoupling of Si and the 6 T thin film.…”

Section: Introductionmentioning

confidence: 99%

Energetic disorder impacts energy-level alignment of alpha-sexithiophene on hydrogen-terminated silicon and silicon oxide

Chen¹,

Hu²,

Wang³

et al. 2022

Mater. Res. Express

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The energy-level alignment at hybrid organic-inorganic interfaces is decisive for the performance of (opto-)electronic devices. We use ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS) to measure the energy-level alignment of vacuum-sublimed -sexithiophene (6T) thin films with HF-etched n-type Si(100) and with Si with a native oxide layer (SiOx). The 6T thin films induce a small (<0.1 eV) downwards band bending into both substrates as shown by XPS. The well-ordered growth of 6T on Si leads to a relatively narrow density of states (DOS) distribution of the highest occupied molecular orbital (HOMO) as shown by UPS. Furthermore, the Fermi-level comes to lie at rather mid-gap position and, consequently, no energy-level bending occurs in the 6T layer. Structural disorder in the 6T thin film on SiOx leads to a broad HOMO DOS distribution and to tailing states into the energy gap. Consequently, downwards energy-level bending (by around 0.20 eV) takes place in the 6T layer.

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Electronic structure of α-sexithiophene ultrathin films grown on

Cited by 8 publications

References 55 publications

Unoccupied electronic states of 2D Si on Ag- 3 -Si(111)

Unoccupied electronic states of 2D Si on Ag- 3 -Si(111)

Spinterface Formation at α-Sexithiophene/Ferromagnetic Conducting Oxide

Energetic disorder impacts energy-level alignment of alpha-sexithiophene on hydrogen-terminated silicon and silicon oxide

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