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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.


Related in: MedlinePlus

STM images of Ge WL on Si(001): (a) hGe = 5.4 Å (Us = +1.80 V, It = 100 pA) and (b) hGe = 6.0 Å (Us = +2.50 V, It = 80 pA). Examples of characteristic features are numbered as follows: nuclei of pyramids (1) and wedges (2) [1 ML high over WL], small pyramids (3) and wedges (2) [2 ML high over WL, a Γ-like wedge [18] is observed in the image (a)], 3 ML high pyramids (5) and wedges (6).
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Figure 4: STM images of Ge WL on Si(001): (a) hGe = 5.4 Å (Us = +1.80 V, It = 100 pA) and (b) hGe = 6.0 Å (Us = +2.50 V, It = 80 pA). Examples of characteristic features are numbered as follows: nuclei of pyramids (1) and wedges (2) [1 ML high over WL], small pyramids (3) and wedges (2) [2 ML high over WL, a Γ-like wedge [18] is observed in the image (a)], 3 ML high pyramids (5) and wedges (6).

Mentions: The hut nucleation goes on during the array further evolution. Figure 4 illustrates this process. An array shown in Figure 4a (hGe = 5.4 Å) consists of 1-ML nuclei ('1' and '2'), 2-ML and 3-ML pyramids and wedges ('3' and '5', '4' and '6' mark pyramids and wedges, respectively).e Figure 4b (hGe = 6.0 Å) demonstrates the simultaneous presence of nuclei ('1' and '2') and 2 ML huts ('3' and '4') with the growth of much higher clusters.


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)

STM images of Ge WL on Si(001): (a) hGe = 5.4 Å (Us = +1.80 V, It = 100 pA) and (b) hGe = 6.0 Å (Us = +2.50 V, It = 80 pA). Examples of characteristic features are numbered as follows: nuclei of pyramids (1) and wedges (2) [1 ML high over WL], small pyramids (3) and wedges (2) [2 ML high over WL, a Γ-like wedge [18] is observed in the image (a)], 3 ML high pyramids (5) and wedges (6).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: STM images of Ge WL on Si(001): (a) hGe = 5.4 Å (Us = +1.80 V, It = 100 pA) and (b) hGe = 6.0 Å (Us = +2.50 V, It = 80 pA). Examples of characteristic features are numbered as follows: nuclei of pyramids (1) and wedges (2) [1 ML high over WL], small pyramids (3) and wedges (2) [2 ML high over WL, a Γ-like wedge [18] is observed in the image (a)], 3 ML high pyramids (5) and wedges (6).
Mentions: The hut nucleation goes on during the array further evolution. Figure 4 illustrates this process. An array shown in Figure 4a (hGe = 5.4 Å) consists of 1-ML nuclei ('1' and '2'), 2-ML and 3-ML pyramids and wedges ('3' and '5', '4' and '6' mark pyramids and wedges, respectively).e Figure 4b (hGe = 6.0 Å) demonstrates the simultaneous presence of nuclei ('1' and '2') and 2 ML huts ('3' and '4') with the growth of much higher clusters.

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