Controlling the Early Stages of Pentacene Growth by Supersonic Molecular Beam Deposition

Wu, Yu San; Toccoli, T.; Koch, Norbert; Iacob, Erica; Pallaoro, Alessia; Rudolf, Petra; Iannotta, Salvatore

doi:10.1103/physrevlett.98.076601

Cited by 76 publications

(76 citation statements)

References 21 publications

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“…The fact that in our case the highest frequencies lattice modes at 122 and 132 cm −1 have intensity comparable to that of the intra-molecular modes ( Figure 5) means that the films are characterized by a high degree of lateral order. This finding is in agreement with experiments showing that SuMBD-grown films grow layer by layer and have larger single crystalline domain in comparison with high-vacuum molecular beam deposition [29]. On the other hand, phonons below 80 cm −1 present dispersion along k(0, 0, k), i.e., normal to the ab plane [23].…”

Section: Resultssupporting

confidence: 91%

“…The apparatus is essentially the same as previously described [29]. The raw material bought from Sigma-Aldrich Italy (Milan, Italy) ( 99.995% of purity) was used after outgassing the source at a temperature slightly lower than the pentacene sublimation temperature.…”

Section: Instrumentationmentioning

confidence: 99%

“…The kinetic energy of the impinging molecules was keep constant for all deposition and the value chosen (about 6.5 eV) was the value that give the best result in term of thin film crystallinity [29,30]. We have characterized 8 freshly prepared samples of increasing thickness (from 11 to 781 Å).…”

Section: Film Preparation and Characterizationmentioning

confidence: 99%

“…Furthermore, a detailed comparison of the Raman spectra of all the three LT, HT and TF polymorphs in the CH bending spectral region is still missing. In this paper we present the Raman spectra of pentacene films grown on Si-SiO x by Supersonic Molecular Beam Deposition (SuMBD) [29,30], as a function of layer thickness and of temperature. The films are characterized by ellipsometry, grazing angle X-ray diffraction, and Raman spectroscopy, and belong to the pure TF phase up the highest obtained thickness (781 Å or ∼52 layers).…”

Section: Introductionmentioning

confidence: 99%

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Raman Identification of Polymorphs in Pentacene Films

et al. 2016

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Abstract:We use Raman spectroscopy to characterize thin films of pentacene grown on Si/SiO x by Supersonic Molecular Beam Deposition (SuMBD). We find that films up to a thickness of about 781 Å (∼ 52 monolayers) all belong to the so-called thin-film (TF) phase. The appearance with strong intensity of some lattice phonons suggests that the films are characterized by good intra-layer order. A comparison of the Raman spectra in the lattice and CH bending spectral regions of the TF polymorph with the corresponding ones of the high-temperature (HT) and low-temperature (LT) bulk pentacene polymorphs provides a quick and nondestructive method to identify the different phases.

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Section: Resultssupporting

confidence: 91%

Section: Instrumentationmentioning

confidence: 99%

Section: Film Preparation and Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Raman Identification of Polymorphs in Pentacene Films

et al. 2016

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“…However, for SuMBD grown pentacene thin films, it is more straightforward to change the grain size by tuning the pentacene kinetic energy (E k ) within the molecular beam. In recent studies on pentacene nucleation and growth, we showed how the pentacene critical nucleus size changes with the kinetic energy of the impinging molecules during the early phase of pentacene growth on SiO 2 /Si [18]. Here we extend this investigation to better understand the correlation between E k and island morphology.…”

Section: Introductionmentioning

confidence: 76%

Key role of molecular kinetic energy in early stages of pentacene island growth

Toccoli²,

Zhang

et al. 2009

Appl. Phys. A

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Organic molecular beam deposition is studied systematically at thermal and hyperthermal regimes aiming at investigating the role of molecular kinetic energy on the growth mechanism of pentacene submonolayers on SiO x /Si. We show that the kinetic energy of the impinging molecule (E k ) plays a crucial role in determining island structure and shape, distribution of island sizes, the crystalline quality of the first monolayer, and even the growth mode of subsequent layers. With increasing E k , the island structure changes from fractal to nonfractal, the shape becomes more anisotropic and the island size more uniform, pointing to correlated island growth. Moreover, while 3D island growth is observed for thermal organic molecular beam de- position, supersonic molecular beam deposition gives rise to layer-by-layer growth, at least for the first two layers. When E k ≥ 5.0 eV, the first monolayer is composed of large single crystalline domains which can extend over up to 10 μm, inferred from comparing atomic force micrographs of height and net transverse shear force. In these growth conditions both the high surface diffusivity and energy redistribution play a major role. We propose a mechanism where the energy dissipation occurring during the molecule-surface collision leads to the reorientation of whole islands during island coalescence, resulting in the elimination of grain boundaries.PACS 72.80.Le · 81.15-z · 79.20Rf · 68.37.Ps · 68.55.J · 34.25.+a

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Grain‐Boundary Evolution in a Pentacene Monolayer

2008

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Organic thin-film transistors (OTFTs) based on pentacene polycrystalline films, for applications ranging from flat-panel displays to radio frequency identification tags, have achieved field-effect mobilities over 5 cm 2 V À1 s À1, [1][2][3][4][5] which is comparable to that of competing amorphous silicon devices. Based on studies of morphology and structure of organic semiconductors, the structural quality of thin films was recognized as the key for achieving high field-effect mobility values.

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Controlling the Early Stages of Pentacene Growth by Supersonic Molecular Beam Deposition

Cited by 76 publications

References 21 publications

Raman Identification of Polymorphs in Pentacene Films

Raman Identification of Polymorphs in Pentacene Films

Key role of molecular kinetic energy in early stages of pentacene island growth

Grain‐Boundary Evolution in a Pentacene Monolayer

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