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CMOS-compatible dense arrays of Ge quantum dots on the Si(001) surface: hut cluster nucleation, atomic structure and array life cycle during UHV MBE growth.

Arapkina LV, Yuryev VA - Nanoscale Res Lett (2011)

Bottom Line: Nuclei of pyramids and wedges were observed on the wetting layer (WL) (M × N) patches starting from the coverage of 5.1 Å and found to have different structures.Its ridge structure does not repeat the nucleus.Further growth of hut arrays results in domination of wedges, and the density of pyramids exponentially drops.

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Affiliation: A, M, Prokhorov General Physics Institute of RAS, 38 Vavilov Street, Moscow, 119991, Russia. vyuryev@kapella.gpi.ru.

ABSTRACT
We report a direct observation of Ge hut nucleation on Si(001) during UHV molecular beam epitaxy at 360°C. Nuclei of pyramids and wedges were observed on the wetting layer (WL) (M × N) patches starting from the coverage of 5.1 Å and found to have different structures. Atomic models of nuclei of both hut species have been built as well as models of the growing clusters. The growth of huts of each species has been demonstrated to follow generic scenarios. The formation of the second atomic layer of a wedge results in rearrangement of its first layer. Its ridge structure does not repeat the nucleus. A pyramid grows without phase transitions. A structure of its vertex copies the nucleus. Transitions between hut species turned out to be impossible. The wedges contain point defects in the upper corners of the triangular faces and have preferential growth directions along the ridges. The derived structure of the {105} facet follows the paired dimer model. Further growth of hut arrays results in domination of wedges, and the density of pyramids exponentially drops. The second generation of huts arises at coverages >10 Å; new huts occupy the whole WL at coverages ~14 Å. Nanocrystalline Ge 2D layer begins forming at coverages >14 Å.

No MeSH data available.


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A structure of hut facets: (a) a structural model of the {105} facet of hut clusters derived from the plots given in Figs. 5 and 6 corresponds to the PD (pairs of dimers) model [39], SA and SB are commonly adopted designations of the monoatomic steps [45]: atoms situated on higher terraces are shown by larger circles. (b) The schematic of the facet superimposed on its STM image (4.3 × 4.4 nm, Us = +3.0 V, It = 100 pA): the [100] direction is parallel to the corresponding base side, the steps rise from the lower right to the upper left corner.
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Figure 7: A structure of hut facets: (a) a structural model of the {105} facet of hut clusters derived from the plots given in Figs. 5 and 6 corresponds to the PD (pairs of dimers) model [39], SA and SB are commonly adopted designations of the monoatomic steps [45]: atoms situated on higher terraces are shown by larger circles. (b) The schematic of the facet superimposed on its STM image (4.3 × 4.4 nm, Us = +3.0 V, It = 100 pA): the [100] direction is parallel to the corresponding base side, the steps rise from the lower right to the upper left corner.

Mentions: The presented models allowed us to deduce a structure of the {105} facets (Figure 7a). This model resulting from the above simple crystallographic consideration corresponds to the paired dimers (PD) [39] rather than more recent rebonded step (RS) model [40,41] which is now believed to be an improvement over the previous PD model proposed by Mo et al.


CMOS-compatible dense arrays of Ge quantum dots on the Si(001) surface: hut cluster nucleation, atomic structure and array life cycle during UHV MBE growth.

Arapkina LV, Yuryev VA - Nanoscale Res Lett (2011)

A structure of hut facets: (a) a structural model of the {105} facet of hut clusters derived from the plots given in Figs. 5 and 6 corresponds to the PD (pairs of dimers) model [39], SA and SB are commonly adopted designations of the monoatomic steps [45]: atoms situated on higher terraces are shown by larger circles. (b) The schematic of the facet superimposed on its STM image (4.3 × 4.4 nm, Us = +3.0 V, It = 100 pA): the [100] direction is parallel to the corresponding base side, the steps rise from the lower right to the upper left corner.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211434&req=5

Figure 7: A structure of hut facets: (a) a structural model of the {105} facet of hut clusters derived from the plots given in Figs. 5 and 6 corresponds to the PD (pairs of dimers) model [39], SA and SB are commonly adopted designations of the monoatomic steps [45]: atoms situated on higher terraces are shown by larger circles. (b) The schematic of the facet superimposed on its STM image (4.3 × 4.4 nm, Us = +3.0 V, It = 100 pA): the [100] direction is parallel to the corresponding base side, the steps rise from the lower right to the upper left corner.
Mentions: The presented models allowed us to deduce a structure of the {105} facets (Figure 7a). This model resulting from the above simple crystallographic consideration corresponds to the paired dimers (PD) [39] rather than more recent rebonded step (RS) model [40,41] which is now believed to be an improvement over the previous PD model proposed by Mo et al.

Bottom Line: Nuclei of pyramids and wedges were observed on the wetting layer (WL) (M × N) patches starting from the coverage of 5.1 Å and found to have different structures.Its ridge structure does not repeat the nucleus.Further growth of hut arrays results in domination of wedges, and the density of pyramids exponentially drops.

View Article: PubMed Central - HTML - PubMed

Affiliation: A, M, Prokhorov General Physics Institute of RAS, 38 Vavilov Street, Moscow, 119991, Russia. vyuryev@kapella.gpi.ru.

ABSTRACT
We report a direct observation of Ge hut nucleation on Si(001) during UHV molecular beam epitaxy at 360°C. Nuclei of pyramids and wedges were observed on the wetting layer (WL) (M × N) patches starting from the coverage of 5.1 Å and found to have different structures. Atomic models of nuclei of both hut species have been built as well as models of the growing clusters. The growth of huts of each species has been demonstrated to follow generic scenarios. The formation of the second atomic layer of a wedge results in rearrangement of its first layer. Its ridge structure does not repeat the nucleus. A pyramid grows without phase transitions. A structure of its vertex copies the nucleus. Transitions between hut species turned out to be impossible. The wedges contain point defects in the upper corners of the triangular faces and have preferential growth directions along the ridges. The derived structure of the {105} facet follows the paired dimer model. Further growth of hut arrays results in domination of wedges, and the density of pyramids exponentially drops. The second generation of huts arises at coverages >10 Å; new huts occupy the whole WL at coverages ~14 Å. Nanocrystalline Ge 2D layer begins forming at coverages >14 Å.

No MeSH data available.


Related in: MedlinePlus