Surfaces island self-assembly

Microcontact printing (pCP, see Fig. 10 for an example) has been used for the spatially resolved modification of gold, silver, or titanium surfaces with SAMs of methyl-terminated alkanethiolates, which favor protein adsorption [99-101], Backfilling around the patterned protein-attractive islands was performed by a subsequent self-assembly of an ethylene-glycol-terminated alkanethiol. In a next step, the hydrophobic methyl-terminated SAMs were covered by adsorbed FN or other cell-adhesion-mediating proteins. 

Abstract. We describe the state-of-the-art in the creation of ordered superlattices of adsorbed atoms, molecules, semiconductor quantum dots, and metallic islands, by means of self-assembly during atomic-beam growth on single crystal surfaces. These surfaces often have long-period reconstructions or strain relief patterns which are used as template for heterogeneous nucleation. However, repulsive adsorbate-adsorbate interactions may also stabilize ordered superlattices, and vertical correlations of growth sequences of buried islands will be discussed in the case of semiconductor quantum dots. We also present new template surfaces considered as particularly promising for the creation of novel island superlattices. 

UPD on Pt(lll) displays inhibited activity in acidic solutions even when small quantities of Cu were deposited, suggesting that this surface lacks sufficient Pt active sites. " Although not involving Pt, Ag-UPD on Au(lll) coated with a self-assembled monolayer (SAM) of decanethiol displayed island size effects. HMRD measurements and STM images found two-electron reductions dominate on islands with 750 Ag atoms and four-electron reductions dominate on islands consisting of 4000 Ag atoms. 

Figure 8 TEM image of self-assembled islands of AU55 (PPh3) 12CI6 clusters on a water surface...

We have discussed certain aspects of self-assembly of quantum dots from thin solid films epitaxially grown on solid substrates. We have considered two principle mechanisms of instability of a planar film that lead to the formation of quantum dots the one associated with epitaxial stress and the one associated with the anisotropy of the film surface energy. We have focused on the case of particularly thin hlms when wethng interactions between the film and the substrate are important and derived nonlinear evolution equations for the him surface shape in the small-slope approximahon. We have shown that wetting interachons between the him and the substrate damp long-wave modes of instability and yield the short-wave instability spectrum that can result in the formahon of spahally-regular arrays of islands. We have discussed the nonlinear evoluhon of such arrays analyhcally, by means of weakly nonlinear analysis, and numerically, far from the instability threshold and have shown... 

The concept of templated self-assembly of quantum dots has been transferred from molecular beam epitaxy to chemical vapour deposition. Here we demonstrate the fabrication of ordered arrays of Ge islands on a Si (100) surface using optical holography for the prepattern and subsequent growth by chemical vapor deposition. The samples were analyzed by atomic force microscopy and photoluminescence. Ordered arrays of Ge islands with a narrow size distribution and intense narrow photoluminescence lines of the islands have been observed. 

Regimented arrays of Ge dots have been deposited on pre-patterned Si (100) surfaces by LPCVD. The Ge dots exhibit a narrower size distribution and an improved luminescence efficiency compared to islands grown on non-pattemed areas of the same sample. Narrow, phonon resolved PL was observed from ordered dot arrays, indicating a low defect density in the structures. The transfer of the technology of templated self assembly from MBE to CVD is promising for future application in nanoelectronic devices. 

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