Scanning Tunneling Microscopy Identification of Atomic-Scale Intermixing on Si(100) at Submonolayer Ge Coverages

Qin, X. R.; Swartzentruber, B. S.; Lagally, M. G.

doi:10.1103/physrevlett.84.4645

Cited by 54 publications

(48 citation statements)

References 30 publications

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“…STM investigations 15,16 of a sub-monolayer Ge deposition on Si (001) substrates have also demonstrated that Ge/Si intermixing occurs randomly on the terraces and not preferentially at steps or points defects. This means that the growth kinetics, i.e.…”

Section: Resultsmentioning

confidence: 99%

“…Provided that a vacancy in the terrace can diffuse to the step, 16 the top terrace of the stripe in our samples is regarded as vacancy-free in comparison to the plain surface. Therefore, at the beginning of each monolayer growth, the mean time for ad-dimers on the top terrace migrating to one edge, t d , can be estimated by the following expressions,…”

Section: Figmentioning

confidence: 99%

“…19,20 This has been confirmed by STM observations. 16 Ab initio studies 21 demonstrated that the S B step grows faster than the S A step, resulting in the formation of the D B step. Oshiyama 20 has suggested that the {311} and {111} facets microscopically originate from D B step bunching.…”

Section: Figmentioning

confidence: 99%

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Positioning of self-assembled Ge islands on stripe-patterned Si(001) substrates

Zhong

Halilovic

Mühlberger

et al. 2003

Journal of Applied Physics

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Abstract:Self-assembled Ge islands were grown on stripe-patterned Si (001) substrates by solid source molecular beam epitaxy. The surface morphology obtained by atomic force microscopy (AFM) and cross-sectional transmission electron microscopy images (TEM) shows that the Ge islands are preferentially grown at the sidewalls of pure Si stripes along [-110] direction at 650 o C or along the trenches, whereas most of the Ge islands are formed on the top terrace when the patterned stripes are covered by a strained GeSi buffer layer. Reducing the growth temperature to 600 o C results in a nucleation of Ge islands both on the top terrace and at the sidewall of pure Si stripes. A qualitative analysis, based on the growth kinetics, demonstrates that the step structure of the stripes, the external strain field and the local critical wetting layer thickness for the islands formation contribute to the preferential positioning of Ge islands on the stripes. I. INTRODUCTIONSelf-assembled quantum dots (SAQD) have become an intensive research topic not only because of their promising device applications 1 but also to understand the fundamental process of strained thin film growth. A frequently employed growth mode of a strained heteroepilayer is the so-called Stranski-Krastanow(SK) mode, where after a thin wetting layer the epilayer releases the misfit strain by 3D island formation. These straightforwardly formed islands can be small and in general dislocation-free, but random in position. Although locally laterally ordered SAQD have been observed, i.e., via the growth of a multilayer of SAQD, 2,3 or the growth of SAQD above a buried strained layer with a dislocation network, 4 or growth of SAQD on a vicinal surface with step-bunching, 5,6 these kinds of short-range ordered SAQD are not adequate for most electronic or optoelectronic device applications. 1 Recently, it was shown that the combination of lithographic etching techniques and the SK growth mode provides a potential to grow long-range spatially ordered SAQD. 7-13 Some interesting phenomena have been observed during the growth of SAQD on patterned substrates. For instance InAs SAQD can be preferentially grown either on the top terraces or at the sidewalls or at the trenches of stripe-patterned GaAs substrates. 7 The number of InAs SAQD can be adjusted by the depth of patterned holes. 8 Ge SAQD are preferentially grown at the edges of selectively grown Si mesas in etched SiO 2 windows, 9,10 while they preferentially grow at the sidewalls of pure Si stripes. 11 These phenomena were discussed from the point of view of either energetics or kinetics. However, no detailed discussion about the growth of SAQD on patterned substrates has been presented so far.It is the purpose of this paper to present a description of a growth mechanism to explain the main features of the Ge island formation on stripe-patterned Si (001) substrates. The preferential positioning of Ge SAQD grown at 650 o C on patterned pure Si stripes with different periodicity and height is analyzed from AFM im...

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Section: Resultsmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

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Positioning of self-assembled Ge islands on stripe-patterned Si(001) substrates

Zhong

Halilovic

Mühlberger

et al. 2003

Journal of Applied Physics

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“…In the case of the system Si=Ge it has been difficult to differentiate between Si and Ge due to their similar electronic structure. Only in rare cases it was possible to distinguish Si and Ge atoms [7,8]. In a recent approach to distinguish between Si and Ge atoms, a termination of the surface with Cl was used [8].…”

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confidence: 99%

Nanowires and Nanorings at the Atomic Level

et al. 2003

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The step-flow growth mode is used to fabricate Si and Ge nanowires with a width of 3.5 nm and a thickness of one atomic layer (0.3 nm) by self-assembly. Alternating deposition of Ge and Si results in the formation of a nanowire superlattice covering the whole surface. One atomic layer of Bi terminating the surface is used to distinguish between the elements Si and Ge. A difference in apparent height is measured in scanning tunneling microscopy images for Si and Ge. Also, different kinds of twodimensional Si=Ge nanostructures like alternating Si and Ge nanorings having a width of 5-10 nm were grown.

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“…1͑b͒, can be explained as resulting from an intermixing process 23 and implies the formation of Ge-Ge or Ge-Si dimers where Ge is the uppermost atom. 24 Theoretical calculations by Lee et al 25 show that at low Ge coverage the p͑2 ϫ 2͒ reconstruction is the most energetically favorable.…”

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confidence: 99%

Early stage of Ge growth on Si(001) vicinal surfaces with an 8° miscut along[110]

et al. 2007

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The atomistic pathway towards the growth of semiconductors heterostructures on vicinal surfaces is investigated in a special experiment. A step-by-step study of the early stages of Ge deposition at T = 873 K on a 8°o ff Si͑001͒ surface miscut along ͓110͔ is performed by scanning tunneling microscopy ͑STM͒. The microscopic processes occurring during growth are identified. Highly resolved STM images show how double height steps, which characterize the clean substrate, evolve by a step flow process generated by addimer chains located at specific positions. This process leads to the formation of metastable single domains until the development of ͕105͖ faceted ripples extending along the whole surface in the miscut direction.

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Scanning Tunneling Microscopy Identification of Atomic-Scale Intermixing on Si(100) at Submonolayer Ge Coverages

Cited by 54 publications

References 30 publications

Positioning of self-assembled Ge islands on stripe-patterned Si(001) substrates

Positioning of self-assembled Ge islands on stripe-patterned Si(001) substrates

Nanowires and Nanorings at the Atomic Level

Early stage of Ge growth on Si(001) vicinal surfaces with an 8° miscut along[110]

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