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Phase transition on the Si(001) clean surface prepared in UHV MBE chamber: a study by high-resolution STM and in situ RHEED.

Arapkina LV, Yuryev VA, Chizh KV, Shevlyuga VM, Storojevyh MS, Krylova LA - Nanoscale Res Lett (2011)

Bottom Line: A fraction of the surface area covered by the c(8 × 8) structure decreased, as the sample cooling rate was reduced.A model of the c(8 × 8) structure formation has been built on the basis of the STM data.Origin of the high-order structure on the Si(001) surface and its connection with the epinucleation phenomenon are discussed.PACS 68.35.B-·68.37.Ef·68.49.Jk·68.47.Fg.

View Article: PubMed Central - HTML - PubMed

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

ABSTRACT
The Si(001) surface deoxidized by short annealing at T ~ 925°C in the ultrahigh vacuum molecuar beam epitaxy chamber has been in situ investigated using high-resolution scanning tunneling microscopy (STM)and redegreesected high-energy electron diffraction (RHEED. RHEED patterns corresponding to (2 × 1) and (4 × 4) structures were observed during sample treatment. The (4 × 4) reconstruction arose at T ≲ 600°C after annealing. The reconstruction was observed to be reversible: the (4 × 4) structure turned into the (2 × 1) one at T ≳ 600°C, the (4 × 4) structure appeared again at recurring cooling. The c(8 × 8) reconstruction was revealed by STM at room temperature on the same samples. A fraction of the surface area covered by the c(8 × 8) structure decreased, as the sample cooling rate was reduced. The (2 × 1) structure was observed on the surface free of the c(8 × 8) one. The c(8 × 8) structure has been evidenced to manifest itself as the (4 × 4) one in the RHEED patterns. A model of the c(8 × 8) structure formation has been built on the basis of the STM data. Origin of the high-order structure on the Si(001) surface and its connection with the epinucleation phenomenon are discussed.PACS 68.35.B-·68.37.Ef·68.49.Jk·68.47.Fg.

No MeSH data available.


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STM images of the clean Si(001) surface prepared in the slow-cooling mode: (a) the surface mainly covered by the (2 × 1) structure (+2.0 V, 100 pA), '1' and '3' are terraces; the height of the row '2' coincides with the height of the terrace '1'; (b) a magnified image taken with atomic resolution (-1.5 V, 150 pA), 'A' is the "rectangle", 'B' marks the dimer rows composing the (2 × 1) structure (separate atoms are seen), 'C' shows structural defects, i.e. the dimers of the uppermost layer oriented along the dimers of the lower (2 × 1) rows.
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Figure 5: STM images of the clean Si(001) surface prepared in the slow-cooling mode: (a) the surface mainly covered by the (2 × 1) structure (+2.0 V, 100 pA), '1' and '3' are terraces; the height of the row '2' coincides with the height of the terrace '1'; (b) a magnified image taken with atomic resolution (-1.5 V, 150 pA), 'A' is the "rectangle", 'B' marks the dimer rows composing the (2 × 1) structure (separate atoms are seen), 'C' shows structural defects, i.e. the dimers of the uppermost layer oriented along the dimers of the lower (2 × 1) rows.

Mentions: Effects of annealing duration and cooling rate on the clean surface structure were studied using STM. It was established that increase of annealing duration to 6 min did not cause any changes of the surface structure. On the contrary, decrease of the sample cooling rate drastically changes the structure of the surface. The STM images of the sample surface for the slow-cooling mode (Figure 1) are presented in Figure 5. The difference of this surface from that of the quenched samples (Figure 2b) is that only a few rows of "rectangles" are observed on it. The order of the "rectangle" positions with the period of 8a remains in such rows. Two adjacent terraces are designated in Figure 5a by '1' and '3'. A row of "rectangles" marked as '2' is situated on the terrace '3'; it has the same height as the terrace '1'. The filled-state image, which is magnified in comparison with the former one, is given in Figure 5b. A part of the surface free of the "rectangles" is occupied by the (2 × 1) reconstruction. Images of the dimer rows with the resolved Si atoms are marked as 'B' in Figure 5b. The "rectangles" are also seen in the image (they are marked as 'A') as well as single defects: dimerized Si atoms ('C') and chaotically located on the surface accumulations of several dimers. Most of these dimers are oriented parallel to dimers of the lower surface and located strictly on the dimer row. The influence of the cooling rate on the surface structure was observed by Kubo et al. [6]: when the sample cooling rate was decreased, the surface reconstruction turned from c(8×8) to c(4 × 2), which was considered as the derivative reconstruction of the (2 × 1) one transformed because of dimer buckling.


Phase transition on the Si(001) clean surface prepared in UHV MBE chamber: a study by high-resolution STM and in situ RHEED.

Arapkina LV, Yuryev VA, Chizh KV, Shevlyuga VM, Storojevyh MS, Krylova LA - Nanoscale Res Lett (2011)

STM images of the clean Si(001) surface prepared in the slow-cooling mode: (a) the surface mainly covered by the (2 × 1) structure (+2.0 V, 100 pA), '1' and '3' are terraces; the height of the row '2' coincides with the height of the terrace '1'; (b) a magnified image taken with atomic resolution (-1.5 V, 150 pA), 'A' is the "rectangle", 'B' marks the dimer rows composing the (2 × 1) structure (separate atoms are seen), 'C' shows structural defects, i.e. the dimers of the uppermost layer oriented along the dimers of the lower (2 × 1) rows.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211275&req=5

Figure 5: STM images of the clean Si(001) surface prepared in the slow-cooling mode: (a) the surface mainly covered by the (2 × 1) structure (+2.0 V, 100 pA), '1' and '3' are terraces; the height of the row '2' coincides with the height of the terrace '1'; (b) a magnified image taken with atomic resolution (-1.5 V, 150 pA), 'A' is the "rectangle", 'B' marks the dimer rows composing the (2 × 1) structure (separate atoms are seen), 'C' shows structural defects, i.e. the dimers of the uppermost layer oriented along the dimers of the lower (2 × 1) rows.
Mentions: Effects of annealing duration and cooling rate on the clean surface structure were studied using STM. It was established that increase of annealing duration to 6 min did not cause any changes of the surface structure. On the contrary, decrease of the sample cooling rate drastically changes the structure of the surface. The STM images of the sample surface for the slow-cooling mode (Figure 1) are presented in Figure 5. The difference of this surface from that of the quenched samples (Figure 2b) is that only a few rows of "rectangles" are observed on it. The order of the "rectangle" positions with the period of 8a remains in such rows. Two adjacent terraces are designated in Figure 5a by '1' and '3'. A row of "rectangles" marked as '2' is situated on the terrace '3'; it has the same height as the terrace '1'. The filled-state image, which is magnified in comparison with the former one, is given in Figure 5b. A part of the surface free of the "rectangles" is occupied by the (2 × 1) reconstruction. Images of the dimer rows with the resolved Si atoms are marked as 'B' in Figure 5b. The "rectangles" are also seen in the image (they are marked as 'A') as well as single defects: dimerized Si atoms ('C') and chaotically located on the surface accumulations of several dimers. Most of these dimers are oriented parallel to dimers of the lower surface and located strictly on the dimer row. The influence of the cooling rate on the surface structure was observed by Kubo et al. [6]: when the sample cooling rate was decreased, the surface reconstruction turned from c(8×8) to c(4 × 2), which was considered as the derivative reconstruction of the (2 × 1) one transformed because of dimer buckling.

Bottom Line: A fraction of the surface area covered by the c(8 × 8) structure decreased, as the sample cooling rate was reduced.A model of the c(8 × 8) structure formation has been built on the basis of the STM data.Origin of the high-order structure on the Si(001) surface and its connection with the epinucleation phenomenon are discussed.PACS 68.35.B-·68.37.Ef·68.49.Jk·68.47.Fg.

View Article: PubMed Central - HTML - PubMed

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

ABSTRACT
The Si(001) surface deoxidized by short annealing at T ~ 925°C in the ultrahigh vacuum molecuar beam epitaxy chamber has been in situ investigated using high-resolution scanning tunneling microscopy (STM)and redegreesected high-energy electron diffraction (RHEED. RHEED patterns corresponding to (2 × 1) and (4 × 4) structures were observed during sample treatment. The (4 × 4) reconstruction arose at T ≲ 600°C after annealing. The reconstruction was observed to be reversible: the (4 × 4) structure turned into the (2 × 1) one at T ≳ 600°C, the (4 × 4) structure appeared again at recurring cooling. The c(8 × 8) reconstruction was revealed by STM at room temperature on the same samples. A fraction of the surface area covered by the c(8 × 8) structure decreased, as the sample cooling rate was reduced. The (2 × 1) structure was observed on the surface free of the c(8 × 8) one. The c(8 × 8) structure has been evidenced to manifest itself as the (4 × 4) one in the RHEED patterns. A model of the c(8 × 8) structure formation has been built on the basis of the STM data. Origin of the high-order structure on the Si(001) surface and its connection with the epinucleation phenomenon are discussed.PACS 68.35.B-·68.37.Ef·68.49.Jk·68.47.Fg.

No MeSH data available.


Related in: MedlinePlus