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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.


STM images of the Si(001) surfaces: (a) the surface with the residual silicon oxide (-1.5 V, 150 pA), annealing at ~925°C for ~2 min; the image is inverted: dark areas correspond to the oxide, the lighter areas represent the deoxidized surface; (b) the clean Si(001) surface (+1.9 V, 70 pA) with the Fourier transform pattern shown in the inset, annealing at ~925°C for ~3 min [14].
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Figure 2: STM images of the Si(001) surfaces: (a) the surface with the residual silicon oxide (-1.5 V, 150 pA), annealing at ~925°C for ~2 min; the image is inverted: dark areas correspond to the oxide, the lighter areas represent the deoxidized surface; (b) the clean Si(001) surface (+1.9 V, 70 pA) with the Fourier transform pattern shown in the inset, annealing at ~925°C for ~3 min [14].

Mentions: Figure 2 demonstrates the STM images of the Si(001) surface after annealing at ~ 925°C of different durations. Figure 2a depicts the early phase of the oxide film removal; the annealing duration is 2 min. A part of the surface is still oxidized: the dark areas in the image correspond to the surface coated with the oxide film. The lighter areas correspond to the purified surface. A structure of ordered "rectangles" (the grey features) is observed on the deoxidizes surface. After longer annealing (for 3 min) and quenching (Figure 1), the surface is entirely purified of the oxide (Figure 2b). It consists of terraces separated by the SB or SA monoatomic steps with the height of ~1.4 Å [3]. Each terrace is composed of rows running along [110] or [] directions. The surface reconstruction is different from the (2 × 1) one. The inset of Figure 2b demonstrates the Fourier transform of this image which corresponds to the c(8 × 8) structure [5]: Reflexes of the Fourier transform correspond to the distance ~31 Å in both [110] and [] directions. Therefore, the revealed structure have a periodicity of ~31 Å that corresponds to eight translations a on the surface lattice of Si(001) along the 〈110〉 directions (a = 3.83 Å is a unit translation length). Rows consisting of structurally arranged rectangular blocks are clearly seen in the empty-state STM image (Figure 2b). They turn by 90° on the neighboring terraces.


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 Si(001) surfaces: (a) the surface with the residual silicon oxide (-1.5 V, 150 pA), annealing at ~925°C for ~2 min; the image is inverted: dark areas correspond to the oxide, the lighter areas represent the deoxidized surface; (b) the clean Si(001) surface (+1.9 V, 70 pA) with the Fourier transform pattern shown in the inset, annealing at ~925°C for ~3 min [14].
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: STM images of the Si(001) surfaces: (a) the surface with the residual silicon oxide (-1.5 V, 150 pA), annealing at ~925°C for ~2 min; the image is inverted: dark areas correspond to the oxide, the lighter areas represent the deoxidized surface; (b) the clean Si(001) surface (+1.9 V, 70 pA) with the Fourier transform pattern shown in the inset, annealing at ~925°C for ~3 min [14].
Mentions: Figure 2 demonstrates the STM images of the Si(001) surface after annealing at ~ 925°C of different durations. Figure 2a depicts the early phase of the oxide film removal; the annealing duration is 2 min. A part of the surface is still oxidized: the dark areas in the image correspond to the surface coated with the oxide film. The lighter areas correspond to the purified surface. A structure of ordered "rectangles" (the grey features) is observed on the deoxidizes surface. After longer annealing (for 3 min) and quenching (Figure 1), the surface is entirely purified of the oxide (Figure 2b). It consists of terraces separated by the SB or SA monoatomic steps with the height of ~1.4 Å [3]. Each terrace is composed of rows running along [110] or [] directions. The surface reconstruction is different from the (2 × 1) one. The inset of Figure 2b demonstrates the Fourier transform of this image which corresponds to the c(8 × 8) structure [5]: Reflexes of the Fourier transform correspond to the distance ~31 Å in both [110] and [] directions. Therefore, the revealed structure have a periodicity of ~31 Å that corresponds to eight translations a on the surface lattice of Si(001) along the 〈110〉 directions (a = 3.83 Å is a unit translation length). Rows consisting of structurally arranged rectangular blocks are clearly seen in the empty-state STM image (Figure 2b). They turn by 90° on the neighboring terraces.

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.