Growth morphologies for the deposition of Para-hexaphenyl molecules on amorphous substrates

Research output: Thesis › Doctoral Thesis

Standard

Growth morphologies for the deposition of Para-hexaphenyl molecules on amorphous substrates. / Lorbek, Stefan.
2021.

Research output: Thesis › Doctoral Thesis

Harvard

Lorbek, S 2021, 'Growth morphologies for the deposition of Para-hexaphenyl molecules on amorphous substrates', Dr.mont., Montanuniversitaet Leoben (000).

APA

Lorbek, S. (2021). Growth morphologies for the deposition of Para-hexaphenyl molecules on amorphous substrates. [Doctoral Thesis, Montanuniversitaet Leoben (000)].

Vancouver

Lorbek S. Growth morphologies for the deposition of Para-hexaphenyl molecules on amorphous substrates. 2021.

Author

Lorbek, Stefan. / Growth morphologies for the deposition of Para-hexaphenyl molecules on amorphous substrates. 2021.

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@phdthesis{92262062a5ac4acaa7b4d76496f9df5c,
title = "Growth morphologies for the deposition of Para-hexaphenyl molecules on amorphous substrates",
abstract = "There is already a large variety of applications on the consumer market made of thin films of organic semiconducting materials. Therefore, it is crucial to understand the formation mechanisms of such organic films. Here, thin films of the aromatic rod-like molecule Para-hexaphenyl (6P) were grown by organic molecular beam epitaxy under ultra-high vacuum conditions. For these experiments, Ar+-bombarded mica and silicon dioxide (SiO2) were used as amorphous substrates. 6P tends to build mounds of nearly upright standing molecules on this kind of substrates. The growth morphology of these thin films was investigated by various ex- and in-situ atomic force microscopy techniques (AFM). One important parameter in nucleation of thin-film growth is the critical nucleus size i*. The analysis of the experiments reveals that the calculated values for i* from rate theory, island-size scaling, and capture-zone scaling (using the generalized Wigner surmise) are in good agreement with each other. 6P on ion-bombarded mica and on SiO2 can exhibit a post-nucleation with a dewetting by virtue of the exposure to air, most probably because of water co-adsorption. After growth, short annealing of 5 to 10 minutes up to a substrate temperature of 423 K was applied to the 6P thin films. AFM phase mode investigations yield that islands shrink, but something remains or changes the surface at the position of the former islands. Kelvin probe force microscopy reveals a change in the contact potential difference at these positions in comparison with positions at remaining 6P islands or pure SiO2. Further, 6P was deposited under a grazing incidence at angles between 70° and 85° with respect to the substrate's surface normal. Steering effects, which are present in inorganic growth under grazing incidence, were not observed for organic thin films of 6P on SiO2. However, there is an evidence of a slight change in the fractal dimension of the resulting 6P islands. Finally, the nucleation of elongated hexagonal islands in subsequent layers was investigated by AFM and simulations using empirical force-fields (EFF) together with molecular dynamics (MD) simulations were performed. The preferable inner angles of the hexagonal islands are (104±2)° and (126±2)°. EFF simulations result in an octagonal structure as an equilibrium shape of the 6P single crystal and MD simulations explain the formation of a hexagonal structure because the 6P molecules have a higher sticking probability at the [10] facet.",
keywords = "organisches D{\"u}nnfilmwachstum, organische d{\"u}nne Filme, aufrechtstehende Molek{\"u}le, 6P, p6P, para-Hexaphenyl, para-Sexiphenyl, Hexaphenyl, Sexiphenyl, AFM, Rasterkraftmikroskopie, FFM, Reibungskraftmikroskopie, TSM, Querscherungsmikroskopie, KPFM, Kelvinsonden Rasterkraftmikroskopie, Kontaktpotenzialdifferenz, CPD, Siliziumdioxid, Siliziumoxid, amorphe Substrate, Glimmer, Ionen-beschossener Glimmer, Bariumfluorid, Bariumdifluorid, kritische Keimgr{\"o}{\ss}e, kritische Inselgr{\"o}{\ss}e, i*, organischeMolek{\"u}lstrahlepitaxie, OMBE, Ratentheorie, Ratenverteilung, Inselgr{\"o}{\ss}enverteilung, Einfangzonenverteilung, verallgemeinerteWigner Vermutung, Aufdampfrate, bimodale Inselgr{\"o}{\ss}enverteilung, bimodales Wachstum, Ablenkungseffekt, streifender Einfall, sechseckig geformte Inseln, UHV, Ultrahochvakuum, Ehrlich-Schwoebel Barriere, Keimbildung, Normierungstheorie, Voronoi-Diagramm, Dirichlet-Zerlegung, Einfangzone, diffusionsbegrenztes Wachstum, DLA, anlagerungsbegrenztesWachstum, ALA, kompakte Insel, dendritische Insel, fraktaleInsel, fraktale Dimension, Monte Carlo Simulation, Energiefeldersimulation, Molek{\"u}ldynamiksimulation, organischeHalbleitermolek{\"u}le, organischer Halbleiter, Muskovit, Heliumionenmikroskop, HIM, Ausheilen, Plasma{\"a}tzen, nat{\"u}rlichgewachsenes Siliziumoxid, thermisch gewachsenes Siliziumoxid, hot-precursor Zustand, hei{\ss}er Pr{\"a}kursorzustand, organic thin-film growth, organic thin films, upright standing molecules, 6P, p6P, para-hexaphenyl, para-sexiphenyl, hexaphenyl, sexiphenyl, AFM, atomic force microscopy, FFM, friction force microscopy, TSM, transverse shear microscopy, KPFM, Kelvin probe force microscopy, contact potential difference, CPD, silicon dioxide, SiO2, amorphous substrates, mica, ion-bombarded mica, barium flouride, BaF2, critical nucleus size, critical island size, i*, organic molecular beam epitaxy, OMBE, rate theory, rate equation, island-size distribution, capture-zone distribution, generalized Wigner surmise, deposition rate, bimodal island-size distribution, bimodal growth, steering effect, grazing incidence, hexagonal shaped islands, UHV, ultra-high vacuum, Ehrlich-Schwoebel barrier, nucleation, scaling theory, Voronoi tessellation, capture zone, diffusion-limited aggregation, DLA, attachment-limited aggregation, ALA, compact island, dendritic island, fractal island, fractal dimension, Monte Carlo simulation, energy-fields simulation, molecular dynamics simulation, organic semiconducting molecules, organic semiconductor, muscovite mica, helium ion microscopy, HIM, annealing, plasma etching, native silicon dioxide, thermally grown silicon dioxide, hot-precursor state",
author = "Stefan Lorbek",
note = "embargoed until null",
year = "2021",
language = "English",
school = "Montanuniversitaet Leoben (000)",

}

RIS (suitable for import to EndNote) - Download

TY - BOOK

T1 - Growth morphologies for the deposition of Para-hexaphenyl molecules on amorphous substrates

AU - Lorbek, Stefan

N1 - embargoed until null

PY - 2021

Y1 - 2021

N2 - There is already a large variety of applications on the consumer market made of thin films of organic semiconducting materials. Therefore, it is crucial to understand the formation mechanisms of such organic films. Here, thin films of the aromatic rod-like molecule Para-hexaphenyl (6P) were grown by organic molecular beam epitaxy under ultra-high vacuum conditions. For these experiments, Ar+-bombarded mica and silicon dioxide (SiO2) were used as amorphous substrates. 6P tends to build mounds of nearly upright standing molecules on this kind of substrates. The growth morphology of these thin films was investigated by various ex- and in-situ atomic force microscopy techniques (AFM). One important parameter in nucleation of thin-film growth is the critical nucleus size i*. The analysis of the experiments reveals that the calculated values for i* from rate theory, island-size scaling, and capture-zone scaling (using the generalized Wigner surmise) are in good agreement with each other. 6P on ion-bombarded mica and on SiO2 can exhibit a post-nucleation with a dewetting by virtue of the exposure to air, most probably because of water co-adsorption. After growth, short annealing of 5 to 10 minutes up to a substrate temperature of 423 K was applied to the 6P thin films. AFM phase mode investigations yield that islands shrink, but something remains or changes the surface at the position of the former islands. Kelvin probe force microscopy reveals a change in the contact potential difference at these positions in comparison with positions at remaining 6P islands or pure SiO2. Further, 6P was deposited under a grazing incidence at angles between 70° and 85° with respect to the substrate's surface normal. Steering effects, which are present in inorganic growth under grazing incidence, were not observed for organic thin films of 6P on SiO2. However, there is an evidence of a slight change in the fractal dimension of the resulting 6P islands. Finally, the nucleation of elongated hexagonal islands in subsequent layers was investigated by AFM and simulations using empirical force-fields (EFF) together with molecular dynamics (MD) simulations were performed. The preferable inner angles of the hexagonal islands are (104±2)° and (126±2)°. EFF simulations result in an octagonal structure as an equilibrium shape of the 6P single crystal and MD simulations explain the formation of a hexagonal structure because the 6P molecules have a higher sticking probability at the [10] facet.

AB - There is already a large variety of applications on the consumer market made of thin films of organic semiconducting materials. Therefore, it is crucial to understand the formation mechanisms of such organic films. Here, thin films of the aromatic rod-like molecule Para-hexaphenyl (6P) were grown by organic molecular beam epitaxy under ultra-high vacuum conditions. For these experiments, Ar+-bombarded mica and silicon dioxide (SiO2) were used as amorphous substrates. 6P tends to build mounds of nearly upright standing molecules on this kind of substrates. The growth morphology of these thin films was investigated by various ex- and in-situ atomic force microscopy techniques (AFM). One important parameter in nucleation of thin-film growth is the critical nucleus size i*. The analysis of the experiments reveals that the calculated values for i* from rate theory, island-size scaling, and capture-zone scaling (using the generalized Wigner surmise) are in good agreement with each other. 6P on ion-bombarded mica and on SiO2 can exhibit a post-nucleation with a dewetting by virtue of the exposure to air, most probably because of water co-adsorption. After growth, short annealing of 5 to 10 minutes up to a substrate temperature of 423 K was applied to the 6P thin films. AFM phase mode investigations yield that islands shrink, but something remains or changes the surface at the position of the former islands. Kelvin probe force microscopy reveals a change in the contact potential difference at these positions in comparison with positions at remaining 6P islands or pure SiO2. Further, 6P was deposited under a grazing incidence at angles between 70° and 85° with respect to the substrate's surface normal. Steering effects, which are present in inorganic growth under grazing incidence, were not observed for organic thin films of 6P on SiO2. However, there is an evidence of a slight change in the fractal dimension of the resulting 6P islands. Finally, the nucleation of elongated hexagonal islands in subsequent layers was investigated by AFM and simulations using empirical force-fields (EFF) together with molecular dynamics (MD) simulations were performed. The preferable inner angles of the hexagonal islands are (104±2)° and (126±2)°. EFF simulations result in an octagonal structure as an equilibrium shape of the 6P single crystal and MD simulations explain the formation of a hexagonal structure because the 6P molecules have a higher sticking probability at the [10] facet.

KW - organisches Dünnfilmwachstum

KW - organische dünne Filme

KW - aufrechtstehende Moleküle

KW - 6P

KW - p6P

KW - para-Hexaphenyl

KW - para-Sexiphenyl

KW - Hexaphenyl

KW - Sexiphenyl

KW - AFM

KW - Rasterkraftmikroskopie

KW - FFM

KW - Reibungskraftmikroskopie

KW - TSM

KW - Querscherungsmikroskopie

KW - KPFM

KW - Kelvinsonden Rasterkraftmikroskopie

KW - Kontaktpotenzialdifferenz

KW - CPD

KW - Siliziumdioxid

KW - Siliziumoxid

KW - amorphe Substrate

KW - Glimmer

KW - Ionen-beschossener Glimmer

KW - Bariumfluorid

KW - Bariumdifluorid

KW - kritische Keimgröße

KW - kritische Inselgröße

KW - i

KW - organischeMolekülstrahlepitaxie

KW - OMBE

KW - Ratentheorie

KW - Ratenverteilung

KW - Inselgrößenverteilung

KW - Einfangzonenverteilung

KW - verallgemeinerteWigner Vermutung

KW - Aufdampfrate

KW - bimodale Inselgrößenverteilung

KW - bimodales Wachstum

KW - Ablenkungseffekt

KW - streifender Einfall

KW - sechseckig geformte Inseln

KW - UHV

KW - Ultrahochvakuum

KW - Ehrlich-Schwoebel Barriere

KW - Keimbildung

KW - Normierungstheorie

KW - Voronoi-Diagramm

KW - Dirichlet-Zerlegung

KW - Einfangzone

KW - diffusionsbegrenztes Wachstum

KW - DLA

KW - anlagerungsbegrenztesWachstum

KW - ALA

KW - kompakte Insel

KW - dendritische Insel

KW - fraktaleInsel

KW - fraktale Dimension

KW - Monte Carlo Simulation

KW - Energiefeldersimulation

KW - Moleküldynamiksimulation

KW - organischeHalbleitermoleküle

KW - organischer Halbleiter

KW - Muskovit

KW - Heliumionenmikroskop

KW - HIM

KW - Ausheilen

KW - Plasmaätzen

KW - natürlichgewachsenes Siliziumoxid

KW - thermisch gewachsenes Siliziumoxid

KW - hot-precursor Zustand

KW - heißer Präkursorzustand

KW - organic thin-film growth

KW - organic thin films

KW - upright standing molecules

KW - 6P

KW - p6P

KW - para-hexaphenyl

KW - para-sexiphenyl

KW - hexaphenyl

KW - sexiphenyl

KW - AFM

KW - atomic force microscopy

KW - FFM

KW - friction force microscopy

KW - TSM

KW - transverse shear microscopy

KW - KPFM

KW - Kelvin probe force microscopy

KW - contact potential difference

KW - CPD

KW - silicon dioxide

KW - SiO2

KW - amorphous substrates

KW - mica

KW - ion-bombarded mica

KW - barium flouride

KW - BaF2

KW - critical nucleus size

KW - critical island size

KW - i

KW - organic molecular beam epitaxy

KW - OMBE

KW - rate theory

KW - rate equation

KW - island-size distribution

KW - capture-zone distribution

KW - generalized Wigner surmise

KW - deposition rate

KW - bimodal island-size distribution

KW - bimodal growth

KW - steering effect

KW - grazing incidence

KW - hexagonal shaped islands

KW - UHV

KW - ultra-high vacuum

KW - Ehrlich-Schwoebel barrier

KW - nucleation

KW - scaling theory

KW - Voronoi tessellation

KW - capture zone

KW - diffusion-limited aggregation

KW - DLA

KW - attachment-limited aggregation

KW - ALA

KW - compact island

KW - dendritic island

KW - fractal island

KW - fractal dimension

KW - Monte Carlo simulation

KW - energy-fields simulation

KW - molecular dynamics simulation

KW - organic semiconducting molecules

KW - organic semiconductor

KW - muscovite mica

KW - helium ion microscopy

KW - HIM

KW - annealing

KW - plasma etching

KW - native silicon dioxide

KW - thermally grown silicon dioxide

KW - hot-precursor state

M3 - Doctoral Thesis

ER -

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