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Polycrystalline domain structure of pentacene thin films epitaxially grown on a hydrogen-terminated Si(111) surface
- Source :
- Physical review. B. 76(16):165424-165424-10
- Publication Year :
- 2007
- Publisher :
- American Physical Society, 2007.
-
Abstract
- Single-monolayer high pentacene (Pn) dendrites grown on a hydrogen-terminated Si(111) surface [H-Si(111)] under ultrahigh vacuum were observed by low-energy electron microscopy and microbeam low-energy electron diffraction analyses. We determined the epitaxial structure (type I) inside a unique polycrystalline domain structure of such dendrites, each of which has six equivalent epitaxial orientations of Pn two-dimensional (2D) unit cells. There are three sets of these cells, which are rotated $\ifmmode\pm\else\textpm\fi{}120\ifmmode^\circ\else\textdegree\fi{}$ relative to each other. Domain boundaries inside each dendrite were successfully observed by scanning tunneling microscopy. In addition, we found another epitaxial relation (type II): the polycrystalline domain structure and lattice parameters are similar to those of the type-I dendrite; however, the 2D unit cells of the type-II dendrite are rotated approximately 90\ifmmode^\circ\else\textdegree\fi{} relative to those of the type-I dendrite. These results suggest that the crystal structure of the dendrites on H-Si(111) is determined mainly by the interaction between Pn molecules. Each dendrite is composed of domains that are exclusively of type I or II. The so-called point-on-line coincidences are found between the Pn 2D lattices of types I and II, and H-Si(111). The higher commensurability of the type-I dendrites than the type-II dendrites results in a higher probability of type-I dendrite formation. Moreover, for both the type-I and type-II dendrites, we found supercell structures. We estimated the minimum interface energy between the dendrite and H-Si(111) from an island's free energy, which is necessary to reproduce the growth of a single-monolayer high dendrite.
- Subjects :
- Materials science
Condensed matter physics
Crystal structure
Condensed Matter Physics
Epitaxy
Surface energy
Electronic, Optical and Magnetic Materials
law.invention
Pentacene
chemistry.chemical_compound
Low-energy electron microscopy
chemistry
Electron diffraction
law
Crystallite
Scanning tunneling microscope
Subjects
Details
- Language :
- English
- ISSN :
- 10980121
- Volume :
- 76
- Issue :
- 16
- Database :
- OpenAIRE
- Journal :
- Physical review. B
- Accession number :
- edsair.doi.dedup.....fcd2d078aecf8b2d54a58341717d7634