| 1. |
- Jemander, S.T., et al.
(författare)
-
STM study of the C-induced Si(100)-c(4×4) reconstruction
- 2002
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Sociaty. - 1098-0121 .- 1550-235X. ; 65:11, s. 115321-
-
Tidskriftsartikel (refereegranskat)abstract
- We report a direct and reliable way to produce the Si(100)-c(4×4) reconstruction by submonolayer deposition from a SiC source and subsequent annealing. Auger electron spectroscopy, low-energy electron diffraction, and scanning tunneling microscopy (STM) investigations reveal that a C amount equivalent to 0.07 monolayers (ML’s) is sufficient to obtain full coverage of the c(4×4) reconstruction. A deposition of 0.035 ML’s C produces a c(4×4) coverage of only 19%, indicating that C is not only present in the c(4×4) areas, but also in the 2×1 areas. There is not enough C to make it a regular part of the c(4×4) reconstruction and we therefore conclude that the c(4×4) reconstruction is strain induced. We find that a combination of the mixed ad-dimer and buckled ad-dimer models explains all main features observed in the STM images. Images of freshly prepared c(4×4) surfaces exhibit a decoration of approximately 50% of the unit cells, which is attributed to perpendicular ad-dimers. Long exposures (>20 h) to the UHV background gas quench these features and the c(4×4) reconstruction appears as if more homogeneous.
|
|
| 2. |
- Jemander, S.T., et al.
(författare)
-
STM study of the surface defects of the (v3×v3)-Sn/Si(1 1 1) surface
- 2001
-
Ingår i: Surface Science. - : Elsevier. - 0039-6028 .- 1879-2758. ; 475:1-3, s. 181-193
-
Tidskriftsartikel (refereegranskat)abstract
- The (v3×v3)-Sn/Si(1 1 1) surface has been studied with scanning tunneling microscopy (STM) and Auger electron spectroscopy, and it is found that it contains basically five different types of defects originating from substitutional atoms and vacancies. The influence the defects have on their immediate neighbourhood is investigated and found to extend to the third nearest (v3×v3) adatom neighbour. Close to some defect constellations, a very local (3×3) periodicity in the apparent height in the STM images is found. This periodicity is shown to be a linear superposition of the perturbations generated by the individual defects in the constellations. The superposition of the height modulation is accurate and linear for a wide range of tip biases, as for combinations of different types of defects. Its linearity is explained in terms of small perturbations in the surface electronic structure. We also provide an explanation why the linearity breaks down when large perturbations are probed with small tip biases.
|
|
| 3. |
- Jemander, S.T., et al.
(författare)
-
Surface structure of Si(100) with submonolayer coverages of C
- 2002
-
Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Elsevier. - 1073-5615 .- 1543-1916. ; 89:1-3, s. 415-419
-
Konferensbidrag (refereegranskat)abstract
- We report a combined STM, LEED and AES study of Si(100) surfaces prepared by coevaporation from two MBE-sources with Si and SiC, respectively. The flux from the SiC source contains 10% C, enabling studies of deposited layers with C-concentrations in the range 0-10%. After room temperature deposition, the structures have been annealed at 600 °C to generate a c(4 × 4) reconstruction. This has previously been reported to contain from 0.0 to 0.5 monolayers (ML) of C. Annealing at 800 °C irreversibly transforms the c(4 × 4) surface to a 2 × 1-reconstructed surface that contains precipitates of SiC. Since only 0.07 ML of C is needed to have 98% of the surface covered with the c(4 × 4) reconstruction, we conclude that the c(4 × 4) reconstruction is impurity-induced rather than having C-atoms in well defined positions within each unit cell. The c(4 × 4) reconstruction is attributed to a basic structure containing buckled parallel ad-dimers, which in approximately 50% of the reconstructed unit cells is decorated with perpendicular dimers. © 2002 Elsevier Science B.V. All rights reserved.
|
|
| 4. |
- Robbie, K., et al.
(författare)
-
Formation of Ni-graphite intercalation compounds on SiC
- 2001
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 64, s. 155401-15540111
-
Tidskriftsartikel (refereegranskat)
|
|
| 5. |
- Sakamoto, K., et al.
(författare)
-
Interaction of metastable molecular oxygen with the dangling bonds of a Si(111)-(7×7) surface
- 2001
-
Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 114-116, s. 489-494
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the interaction between metastable molecular oxygen and the adatom dangling bonds modified by the adsorption of atomic oxygen into the back-bonds of a Si(111)-(7×7) surface. Ultraviolet photoelectron spectroscopy shows that the metastable states increase in intensity faster but with a decrease in its saturated intensity as the coverage of atomic oxygen increases. This result suggests that the number of modified dangling bonds is not the only important factor for the adsorption process of metastable oxygen. Taking into account the observation of modified dangling bonds with different density of states in scanning tunneling microscopy, we conclude that the adsorption of the metastable oxygen species correlates closely with the density of states of the dangling bond.
|
|
| 6. |
- Uhrberg, Roger, et al.
(författare)
-
Electronic structure of Sn/Si(111) √3×√3 : Indications of a low-temperature phase
- 2000
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 62:12, s. 8082-8086
-
Tidskriftsartikel (refereegranskat)abstract
- The Sn/Si(111) √3×√3 surface has been studied by photoelectron spectroscopy, low-energy electron diffraction (LEED), and scanning tunneling microscopy. Unlike Sn/Ge(111), the Sn/Si(111) surface shows a √3×√3 LEED pattern at low temperature also (70 K). The electronic structure, however, is inconsistent with a pure √3×√3 phase. Sn 4d spectra exhibit two major components and the valence band shows two surface bands. These features have been associated with the low-temperature 3×3 phase in the case of Sn/Ge(111). The similarity in the electronic structure points to stabilization of a low-temperature phase for Sn/Si(111) also, but at a significantly lower temperature (<70 K).
|
|
| 7. |
- Zhang, Hanmin, et al.
(författare)
-
Origin of 3 × 3 diffraction on the Sn1-xSix/Si(1 1 1) v3 × v3 surface
- 2003
-
Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 531:1, s. 21-28
-
Tidskriftsartikel (refereegranskat)abstract
- An evolution of an apparent 3 × 3 low-energy electron diffraction (LEED) pattern has been observed for the Sn1-xSix/Si(1 1 1) v3 × v3 surface alloy. The origin of this additional diffraction has been investigated in detail by scanning tunneling microscopy (STM). The 3 × 3 diffraction, which appears after annealing, is associated with the arrangement of the Sn and substitutional Si atoms in the surface layer, forming many local structures such as honeycombs, hexagons, and atomic lines. As revealed by Fourier-transforms of the STM-images, these local structures are the origins of the 3 × 3 diffraction and a weak 23×3 streaky background superposed on the 3 × 3 LEED pattern. © 2003 Elsevier Science B.V. All rights reserved.
|
|
| 8. |
|
|
