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A promising routine to fabricate GeSi nanowires via self-assembly on miscut Si (001) substrates.

Zhong Z, Gong H, Ma Y, Fan Y, Jiang Z - Nanoscale Res Lett (2011)

Bottom Line: These results proposed that the formation of the nanowire was energetically driven under growth kinetic assistance.Three-dimensionally self-assembled GeSi nanowires were first realized via multilayer Ge growth separated with Si spacers.These GeSi nanowires were readily embedded in Si matrix and compatible with the sophisticated Si technology, which suggested a feasible strategy to fabricate nanowires for fundamental studies and a wide variety of applications.PACS: 81.07.Gf, 81.16.Dn, 68.65.-k, 68.37.Ps.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Handan Str, 220, Shanghai 200433, China. zhenyangz@fudan.edu.cn.

ABSTRACT
: Very small and compactly arranged GeSi nanowires could self-assembled on vicinal Si (001) substrates with ~8° off toward ⟨110⟩ during Ge deposition. The nanowires were all oriented along the miscut direction. The small ration of height over width of the nanowire indicated that the nanowires were bordered partly with {1 0 5} facets. These self-assembled small nanowires were remarkably influenced by the growth conditions and the miscut angle of substrates in comparison with large dome-like islands obtained after sufficient Ge deposition. These results proposed that the formation of the nanowire was energetically driven under growth kinetic assistance. Three-dimensionally self-assembled GeSi nanowires were first realized via multilayer Ge growth separated with Si spacers. These GeSi nanowires were readily embedded in Si matrix and compatible with the sophisticated Si technology, which suggested a feasible strategy to fabricate nanowires for fundamental studies and a wide variety of applications.PACS: 81.07.Gf, 81.16.Dn, 68.65.-k, 68.37.Ps.

No MeSH data available.


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AFM image (0.5 × 0.5 μm2) of the surface morphology after. (a) 1.2 nm Ge at 560°C, (b) 1.5 nm Ge at 580°C, (c) 1.2 nm Ge at 600°C (phase image), on vicinal Si (001) substrates with ~8° off toward ⟨110⟩, (d) height of nanowires vs growth temperature. The black arrows in (a), (b), and (c) denote the miscut direction of the substrates. The dashed line in (d) is for eye-guide. The numbers in (d) are the corresponding amount of nominal Ge deposition.
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Figure 2: AFM image (0.5 × 0.5 μm2) of the surface morphology after. (a) 1.2 nm Ge at 560°C, (b) 1.5 nm Ge at 580°C, (c) 1.2 nm Ge at 600°C (phase image), on vicinal Si (001) substrates with ~8° off toward ⟨110⟩, (d) height of nanowires vs growth temperature. The black arrows in (a), (b), and (c) denote the miscut direction of the substrates. The dashed line in (d) is for eye-guide. The numbers in (d) are the corresponding amount of nominal Ge deposition.

Mentions: It is well known that on normal Si (001) substrates dome-like GeSi islands can be obtained with sufficient Ge deposition [24], and the growth conditions affect the formation of the islands [25]. We found that the nanostructures grown on vicinal Si (001) substrates also depended on the amount of deposited Ge and the growth conditions, as shown in Figure 2. With sufficient Ge deposition, dome-like islands appeared in addition to the nanowires, as shown in Figure 2a-c. Such dome-like islands on vicinal Si (001) substrates were nearly the same as those on normal Si (001) substrates. The nanowires were still obtained and covered most of the surface area in these samples. The orientation of the nanowire, denoted by black arrows in Figure 2a-c, was all along the miscut direction. More interestingly, statistical analyses of the height of the nanowires of these samples demonstrated that the height of the nanowires tended to decrease with increasing growth temperature, as shown in Figure 2d. While the width of the nanowire was not so much different. Such a tendency of the height was related to the temperature-dependent Ge-Si intermixing [26]. The misfit strain due to the lattice mismatch between the epilayer and the substrate can be relaxed by three-dimensional (3D) growth and/or by alloying due to intermixing. At a low growth temperature, Ge-Si intermixing can be considerably reduced. Therefore the misfit strain was mainly relaxed by the 3D growth, which gave rise to the formation of nanowires with a large height. Whereas, at a high growth temperature, strong Ge-Si intermixing can efficiently relax the misfit strain. As a result, the finally formed nanowires had a small height. This result suggested that the formation of the nanowires was energetically driven. On the other hand, to obtain pronounced nanowires, the growth temperature should not be too high.


A promising routine to fabricate GeSi nanowires via self-assembly on miscut Si (001) substrates.

Zhong Z, Gong H, Ma Y, Fan Y, Jiang Z - Nanoscale Res Lett (2011)

AFM image (0.5 × 0.5 μm2) of the surface morphology after. (a) 1.2 nm Ge at 560°C, (b) 1.5 nm Ge at 580°C, (c) 1.2 nm Ge at 600°C (phase image), on vicinal Si (001) substrates with ~8° off toward ⟨110⟩, (d) height of nanowires vs growth temperature. The black arrows in (a), (b), and (c) denote the miscut direction of the substrates. The dashed line in (d) is for eye-guide. The numbers in (d) are the corresponding amount of nominal Ge deposition.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211410&req=5

Figure 2: AFM image (0.5 × 0.5 μm2) of the surface morphology after. (a) 1.2 nm Ge at 560°C, (b) 1.5 nm Ge at 580°C, (c) 1.2 nm Ge at 600°C (phase image), on vicinal Si (001) substrates with ~8° off toward ⟨110⟩, (d) height of nanowires vs growth temperature. The black arrows in (a), (b), and (c) denote the miscut direction of the substrates. The dashed line in (d) is for eye-guide. The numbers in (d) are the corresponding amount of nominal Ge deposition.
Mentions: It is well known that on normal Si (001) substrates dome-like GeSi islands can be obtained with sufficient Ge deposition [24], and the growth conditions affect the formation of the islands [25]. We found that the nanostructures grown on vicinal Si (001) substrates also depended on the amount of deposited Ge and the growth conditions, as shown in Figure 2. With sufficient Ge deposition, dome-like islands appeared in addition to the nanowires, as shown in Figure 2a-c. Such dome-like islands on vicinal Si (001) substrates were nearly the same as those on normal Si (001) substrates. The nanowires were still obtained and covered most of the surface area in these samples. The orientation of the nanowire, denoted by black arrows in Figure 2a-c, was all along the miscut direction. More interestingly, statistical analyses of the height of the nanowires of these samples demonstrated that the height of the nanowires tended to decrease with increasing growth temperature, as shown in Figure 2d. While the width of the nanowire was not so much different. Such a tendency of the height was related to the temperature-dependent Ge-Si intermixing [26]. The misfit strain due to the lattice mismatch between the epilayer and the substrate can be relaxed by three-dimensional (3D) growth and/or by alloying due to intermixing. At a low growth temperature, Ge-Si intermixing can be considerably reduced. Therefore the misfit strain was mainly relaxed by the 3D growth, which gave rise to the formation of nanowires with a large height. Whereas, at a high growth temperature, strong Ge-Si intermixing can efficiently relax the misfit strain. As a result, the finally formed nanowires had a small height. This result suggested that the formation of the nanowires was energetically driven. On the other hand, to obtain pronounced nanowires, the growth temperature should not be too high.

Bottom Line: These results proposed that the formation of the nanowire was energetically driven under growth kinetic assistance.Three-dimensionally self-assembled GeSi nanowires were first realized via multilayer Ge growth separated with Si spacers.These GeSi nanowires were readily embedded in Si matrix and compatible with the sophisticated Si technology, which suggested a feasible strategy to fabricate nanowires for fundamental studies and a wide variety of applications.PACS: 81.07.Gf, 81.16.Dn, 68.65.-k, 68.37.Ps.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Handan Str, 220, Shanghai 200433, China. zhenyangz@fudan.edu.cn.

ABSTRACT
: Very small and compactly arranged GeSi nanowires could self-assembled on vicinal Si (001) substrates with ~8° off toward ⟨110⟩ during Ge deposition. The nanowires were all oriented along the miscut direction. The small ration of height over width of the nanowire indicated that the nanowires were bordered partly with {1 0 5} facets. These self-assembled small nanowires were remarkably influenced by the growth conditions and the miscut angle of substrates in comparison with large dome-like islands obtained after sufficient Ge deposition. These results proposed that the formation of the nanowire was energetically driven under growth kinetic assistance. Three-dimensionally self-assembled GeSi nanowires were first realized via multilayer Ge growth separated with Si spacers. These GeSi nanowires were readily embedded in Si matrix and compatible with the sophisticated Si technology, which suggested a feasible strategy to fabricate nanowires for fundamental studies and a wide variety of applications.PACS: 81.07.Gf, 81.16.Dn, 68.65.-k, 68.37.Ps.

No MeSH data available.


Related in: MedlinePlus