Artificial epitaxy (graphoepitaxy) of semiconductors

Givargizov, E. I.; Limanov, A. B.; Zadorozhnaya, L. A.; Lazarenko, M.; Lukina, I.G.

doi:10.1016/0022-0248(83)90071-4

Cited by 19 publications

(5 citation statements)

References 11 publications

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“…To a certain extent, the present orientation mechanism for T iso ≤ 200 °C bears some smilarity with so-called grapho-epitaxial orientation but the main difference is that the molecular structure of the K−BrBz substrate is essential for the efficient nucleation of P3HT crystalline domains at temperatures below 180 °C. As a matter of fact, attempts to orient other poly(3-alkylthiophenes), e.g., poly(3-butylthiophene) and poly(3-decylthiophene), at different isothermal crystallization temperatures on the K−BrBz substrate were not successful.…”

Section: Resultsmentioning

confidence: 72%

Highly Oriented and Nanotextured Films of Regioregular Poly(3-hexylthiophene) Grown by Epitaxy on the Nanostructured Surface of an Aromatic Substrate

et al. 2010

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A simple method for the nanotexturing and orientation of regioregular poly(3-hexylthiophene) (P3HT) thin films has been developed. Epitaxial growth of P3HT on the surface of an aromatic salt (potassium 4-bromobenzoate) (K-BrBz) leads to highly oriented and nanotextured P3HT films which consist of a regular network of interconnected semicrystalline domains oriented along two preferential in-plane directions. The overall crystallinity and the level of in-plane orientation of the P3HT films are controlled by the temperature of isothermal crystallization (T iso ). Well-defined electron diffraction patterns with sharp reflections obtained for T iso =180 °C indicate that the crystalline domains grow with a unique (1 0 0) P3HT contact plane on the K-BrBz substrate with the P3HT chains oriented along the [0 (2 1] K-BrBz directions of the substrate. During the annealing of the polymer film, the surface of the aromatic salt undergoes a topographic reconstruction resulting in a regular nanostructured "hill and valley" topography that templates and orients the growth of P3HT. Preferred orientation of P3HT crystalline domains occurs at step edges of the substrate and is favored by the matching between the layer period of P3HT and the terrace height of the K-BrBz substrate.

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Section: Resultsmentioning

confidence: 72%

Highly Oriented and Nanotextured Films of Regioregular Poly(3-hexylthiophene) Grown by Epitaxy on the Nanostructured Surface of an Aromatic Substrate

et al. 2010

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“…At the mesoscale, the mechanism of nucleus formation is based on the directional coalescence of smaller amorphous aggregates located along the PTFE macrosteps. The preferential nucleation of crystals at macrosteps has been quantitatively demonstrated by Chakraverty and Pound. , Such a preferential nucleation process involves (i) the preorganization of the amorphous aggregates that are aligned along the PTFE macrosteps and (ii) an important lowering of the free energy of nucleation.…”

Section: Discussionmentioning

confidence: 96%

“…A significant mobility of the molecules, as well as of the entire aggregates, is required to achieve coalescence and reorganization of the amorphous preagregates into crystalline domains. High translational and rotational aggregate mobilities have been reported for metal clusters with sizes of up to several nanometers and are also likely to be at play in the case of amorphous organic clusters . Both the anisotropy of wetting and the low surface tension of PTFE are likely to control the processes of aggregate mobility and coalescence.…”

Section: Discussionmentioning

confidence: 99%

Highly Ordered Titanyl Phthalocyanine Films Grown by Directional Crystallization on Oriented Poly(Tetrafluoroethylene) Substrate

Brinkmann¹,

Wittmann²,

and³

et al. 2002

Chem. Mater.

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Highly oriented films of titanyl phthalocyanine (TiOPc) were obtained by high-vacuum sublimation onto an oriented poly(tetrafluoroethylene) (PTFE) substrate. The dependence of the structure and morphology on deposition parameters (substrate temperature T s, deposition time t, and deposition rate τ) was followed by X-ray diffraction, transmission electron microscopy (TEM), and atomic force microscopy (AFM) to uncover the origin of the oriented growth process. At T s = 100 °C, an original growth mechanism was observed whereby α-TiOPc microcrystallites were formed by the static coalescence and reorganization of small amorphous aggregates in close contact. Nucleation of α-TiOPc is initiated at the PTFE macrosteps from which oriented crystallization propagates, leading to uniform α-TiOPc films with a twinned texture and a dense (0 1 0) contact plane. The molecules are in an edge-on orientation, with their molecular plane oriented parallel to the PTFE chains. At the mesoscale, the nucleation of crystalline α-TiOPc involves the alignment and oriented coalescence of amorphous prenucleation aggregates along the PTFE macrosteps, i.e., a graphoepitaxial process. At the molecular scale, it is proposed that the TiOPc orientation and the preferential nucleation of the α polymorph are enforced by the topography and structure of the PTFE macrosteps in conjunction with the requirement for a minimal nucleation free energy. The optical absorption of the films in the near infrared is found to be strongly correlated with the structural and morphological modifications in the films. The oriented character of the α-TiOPc films results in a strong polarization of the 850-nm band perpendicular to the PTFE chain axis direction.

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“…This situation is similar to that observed in the case of PFTE. It has been shown that pentacene nanocrystallites grow in a confined manner between PTFE fibrils giving rise to a growth mechanism similar to grapho-epitaxy. , However, in the case of the PC substrates, the fact that ZnPc, pentacene, and the bisazo dye grow with one preferred contact plane on the PC substrate may indicate a preferred epitaxial interaction at the overlayer/PC interface. A detailed analysis of the crystalline structure of the PC surface, using grazing incidence X-ray diffraction, is necessary in order to fully discriminate between epitaxy and grapho-epitaxy on this oriented and nanostructured surface.…”

Section: Resultsmentioning

confidence: 99%

Oriented and Nanostructured Polycarbonate Substrates for the Orientation of Conjugated Molecular Materials and Gold Nanoparticles

et al. 2007

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A simple method to prepare large areas of polycarbonate (PC) alignment layers with a high degree of polymer chain orientation, a periodic and oriented nanoscale pattern, and a controlled surface roughness is presented. The method involves three steps: (i) the preparation of a film of bisphenol A polycarbonate in its glassy state, (ii) the near-surface orientation of the polymer chains by rubbing, and (iii) exposure to vapors of acetone which acts as a plasticizer removing the microgrooves formed by rubbing and promotes solvent induced crystallization of PC. The resulting surface of the PC films is oriented and nanostructured, it consists of the periodic alternation of edge-on oriented crystalline lamellae and amorphous interlamellar zones with a total periodicity of ∼20 nm. The roughness of the oriented and nanostructured PC layers can be tuned by adjusting the exposure time to the solvent. The PC films exhibit a high orienting ability for various materials grown from the vapor phase, e.g., conjugated organic semiconductors and dyes (pentacene, phthalocyanine, bisazo dye) and metallic nanoparticles. Zinc phthalocyanine nanocrystallites and gold nanoparticles are observed to orient parallel to the crystalline lamellae of the PC substrate and not, as observed for polyimides, parallel to the polymer chain direction. It is proposed that the shallow surface nanocorrugation associated with the semicrystalline structure of the PC layers enforces the orientation of the ZnPc nanocrystallites and the gold nanoparticles.

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Artificial epitaxy (graphoepitaxy) of semiconductors

Cited by 19 publications

References 11 publications

Highly Oriented and Nanotextured Films of Regioregular Poly(3-hexylthiophene) Grown by Epitaxy on the Nanostructured Surface of an Aromatic Substrate

Highly Oriented and Nanotextured Films of Regioregular Poly(3-hexylthiophene) Grown by Epitaxy on the Nanostructured Surface of an Aromatic Substrate

Highly Ordered Titanyl Phthalocyanine Films Grown by Directional Crystallization on Oriented Poly(Tetrafluoroethylene) Substrate

Oriented and Nanostructured Polycarbonate Substrates for the Orientation of Conjugated Molecular Materials and Gold Nanoparticles

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