Two-dimensional periodic alignment of self-assembled Ge islands on patterned Si(001) surfaces

Kitajima, Takayuki; Liu, Bing; Leone, Stephen R.

doi:10.1063/1.1434307

Cited by 80 publications

(61 citation statements)

References 16 publications

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“…10 This influence of the growth temperature on ad-dimers (or adatoms) may contribute to the formation of Ge islands on the top terrace of the Si mesas at 570 o C observed in Ref. 13. In addition, due to the absence of a Si buffer layer in the samples before the Ge deposition in Ref.…”

Section: A Effect Of the Growth Temperaturementioning

confidence: 99%

“…In addition, due to the absence of a Si buffer layer in the samples before the Ge deposition in Ref. 13, the roughness on the terraces 25 and of the step edges 26 will also contribute to the formation of Ge islands on the top and/or the edge of the top terrace by reducing the migration of ad-dimers. …”

Section: A Effect Of the Growth Temperaturementioning

confidence: 99%

“…(1) where l 1 and l 2 (l 1 +l 2 =w, width of the top terrace) are the distances between the original addimer position and the two edges of the top terrace of the stripes, respectively; D is the diffusion constant, is the surface lattice constant (3.84Å), f is the hopping rate, a γ (~10 13 ) is the prefactor, k B is the Boltzmann constant, T denotes the growth temperature, E b is the diffusion barrier. The maximum mean migration time , t dmax, is for ad-dimers at the center of the top terrace.…”

Section: Figmentioning

confidence: 99%

“…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][8][9][10][11][12][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.…”

Section: Introductionmentioning

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: A Effect Of the Growth Temperaturementioning

confidence: 99%

Section: A Effect Of the Growth Temperaturementioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…We utilize the Ge QDs' tendency to nucleate on locally tensile stressed sites to control the spatial position. The ordered nucleation of the Ge QDs has been demonstrated to be realized by introducing lithographically defined mesa structures [2], or misfit dislocation networks [3] onto the Ge/Si(001) substrate surfaces. The vertical alignment of QDs utilizing the local strain on the apex of the buried QDs has also been reported in the Ge/Si layered structure growth [4].…”

Section: Introductionmentioning

confidence: 99%

Confinement of one-dimensional electrons in dimer row segments at Ge/Si(001) surfaces

Hirayama

2004

Science and Technology of Advanced Materials

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During the initial growth, Si(001) surfaces were covered by thin Ge wetting layers. At the wetting layer surfaces, Ge atoms were reconstructed into dimers, which were aligned along the [110] direction to form one-dimensional (1D) 'dimer rows'. In addition, the dimer rows were partitioned by dimer vacancy lines at the Ge/Si(001) surfaces. As a result, the surfaces were covered spontaneously by an array of 1D dimer row segments. Scanning tunneling microscope images demonstrated that the 1D free-electrons in the dimer rows are confined in each segment and form an ultra-high density array of 1D quantum wells at the surfaces. q

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Formation and optical properties of Ge quantum dots selectively grown on patterned Si(001) substrates

Nguyen

Thanh

Yam

et al. 2004

phys. stat. sol. (a)

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Single and stacked layers of Ge/Si quantum dots (QDs) were grown in windows patterned by electronbeam lithography on oxidized Si(001) substrates. A Si buffer layer was selectively deposited in the windows prior to Ge growth, that plays an important role for nucleation of Ge dots. The Si buffer layer evolves towards [113] faceted pyramids, which reduces the area of the topmost (001) surface available for Ge nucleation. By controlling the top facet area of the Si buffer layers, only one dot per circular window and a high cooperative arrangement of dots on a stripe can be observed. In stacked layers, the dot homogeneity can be improved through the adjustment of the Ge deposited amount in the upper layers. The optical properties of these structures measured by photoluminescence spectroscopy are also reported. In comparison with self-assembled QDs, we observed, both in single and stacked layers, the absence of the wetting-layer contribution and an energy blue shift, confirming therefore the dot formation by selective growth.

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Two-dimensional periodic alignment of self-assembled Ge islands on patterned Si(001) surfaces

Cited by 80 publications

References 16 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

Confinement of one-dimensional electrons in dimer row segments at Ge/Si(001) surfaces

Formation and optical properties of Ge quantum dots selectively grown on patterned Si(001) substrates

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