Evolution of Ge/Si(100) islands: Island size and temperature dependence

Chaparro, S. A.; Zhang, Y.; Drucker, Jeffery; Chandrasekhar, D.; Smith, David J.

doi:10.1063/1.372168

Cited by 151 publications

(102 citation statements)

References 20 publications

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“…3(b) indicating the existence of threading dislocation. The dislocation in ~25 nm sized dot is distinguished from that the dislocation is introduced when the dot size exceeds ~100 nm on the planar substrate [13]. This phenomenon is also observed at the Ge dots on patterned Si substrate with the same pattern size without SiO 2 mask [6].…”

Section: Resultsmentioning

confidence: 84%

Study of growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on nanometer‐scale patterned SiO₂/Si(001) substrates

Yoon

Kim

et al. 2009

Physica Status Solidi (b)

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The growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on patterned SiO2/Si(001) substrates by molecular beam epitaxy were studied. The hexagonally ordered Si holes with 30 nm thick SiO2 mask layer having ∼25 nm diameter, ∼40 nm center‐to‐center distance, and density of ∼7 × 1010 cm–2, were formed using self‐assembled diblock copolymer, composed of polystyrene and poly(methyl methacrylate) (PS‐b ‐PMMA). The multiple Ge nuclei are selectively formed along the periphery of the individual Si holes and these nuclei subsequently coalesce forming single dot with an identical size of patterns. The strain of dots is relaxed up to 80%. The lattice planes of some Ge dots are found to be tilted from those of Si substrates. The Ge dots have dislocations at the interface with Si substrate even at the small size of ∼25 nm, resulting from the limited elastic relaxation in the confined patterned structure. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Resultsmentioning

confidence: 84%

Study of growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on nanometer‐scale patterned SiO₂/Si(001) substrates

Yoon

Kim

et al. 2009

Physica Status Solidi (b)

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“…The pyramid-to-dome shape transition occurs due to better strain relaxation in domes, as compared to pyramids. The latter effect is caused by a higher height-to-base ratio of dome-shaped islands [7]. However, the detailed mechanism of the transition has not been established yet [2].…”

Section: Theoretical Modelmentioning

confidence: 98%

“…At T g > 550 °С the islands initially grow as square-based pyramids. As the islands reach the certain critical volume, a pyramid-to-dome transition occurs through the formation of steeper facets [7][8][9][10]. It should be mentioned that the growth process can be significantly influenced by the kinetic limitations.…”

Section: Theoretical Modelmentioning

confidence: 98%

“…It was found from the microscopic and X-ray studies of nanoislands [5][6][7][8][9][10][11] that, depending on the growth temperature T g and nominal thickness of the deposited Ge, d Ge , both mono-and multimodal island size distribution can be observed. The resulting morphology is related to the formation of pyramidal and/or dome-like islands during MBE process (Fig.…”

Section: Theoretical Modelmentioning

confidence: 99%

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Effect of surface energy minima on the shape of self‐induced SiGe nanoislands

Yaremko

Dzhagan

Lytvyn

et al. 2005

Physica Status Solidi (b)

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The results of a numerical modelling of the influence of discrete surface energy minima on the island shape transition are reported. The real composition of self-induced (Ge)SiGe/Si nanoislands grown at high temperatures is taken into account in deriving the expression of the island total energy. The simulated values of the critical island size at which the transition occurs are compared with those observed in experiments.

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“…There are many other relevant details, especially the role of strain energy, which increases with island size until coherence is lost by introducing misfit dislocations, and various types of islands, surrounded by trenches for strain relief at higher temperatures [14]. At lower temperature, the wetting layer thickness can be > 3 ML, but extra layers are metastable, and disappear on annealing, especially rapidly once dislocated islands have formed, due to dimer diffusion energies of ~ 1 eV.…”

Section: Comparison Of Ge/si(001) With Cu/cu(111)mentioning

confidence: 99%

Time-Dependent Capture Numbers with Repulsive Pair Interactions: Cu/Cu(111) and Ge/Si(001)

2002

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Recent experiments and calculations have shown that weak repulsive interactions between adsorbate atoms may shift nucleation kinetics from the well-known diffusion limit towards the attachment-limited case. The distinctions between diffusion-and attachment-limited kinetics are clarified, and the increased importance of the transient nucleation regime in the latter case is shown to be due to a combination of delayed nucleation and reduced capture. A time-dependent interpolation scheme between attachment-and diffusion-limited capture numbers is proposed, and tested against KMC simulations. Using this scheme to interpret recent STM results on Cu/Cu(111), bounds on the maximum adatom-adatom potential repulsive energy of 12±2 meV are deduced. Time-dependent effects also occur in the growth and ripening of strained Ge islands on Si(001), and the similarities and differences between these two systems are discussed. RATE EQUATIONS CONTAINING SELF-CONSISTENT CAPTURE NUMBERSRate equations have been used successfully to analyze data, notably of the nucleation density n x , as a function of experimental variables, usually the flux F (or equivalently deposition rate R) and the substrate temperature T [1-3]. The reaction rates in each equation, e.g. for the single adatom density n 1 , are of the form 2σ 1 D 1 n 1 2 (for the rate of adatoms forming pairs) or σ x D 1 n 1 n x (for the rate of adatoms joining stable clusters). In these terms σ 1 and σ x are capture numbers, and D 1 is the single-adatom diffusion coefficient. This paper discusses the determination of capture numbers, when there may be barriers for attachment of adatoms to other adatoms and to clusters. The full mathematical and computational details are given in a companion paper [4].Although the distinction between diffusion-limited and attachment-limited kinetics is generally well known, there have not been many explorations of such issues in connection with epitaxial crystal growth. But several recent Scanning Tunneling Microscopy (STM) experiments at low temperatures on smooth metal surfaces [5,6] and associated ab-initio calculations [7,8] have highlighted attachment-limited behavior, due to the presence of repulsive barriers between adatoms. In particular, we show that capture numbers exhibit these two limits, and indicate how the two limits can be combined to give generally applicable, including time-dependent, forms.Repulsive barriers modify the results of conventional (sometimes called classical) nucleation theory (CNT), by extending the transient nucleation regime to higher dose. New formulae are given for the capture numbers on the assumption of radial symmetry, and the expressions are tested against kinetic Monte Carlo (KMC) simulations. As a result, the maximum repulsive interaction energies can be reliably extracted from recent experiments on close-packed metal surfaces; here we concentrate on Cu/Cu(111). The methods may also be applied to other systems in future, and we compare our results qualitatively with Ge/Si(001).

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Evolution of Ge/Si(100) islands: Island size and temperature dependence

Cited by 151 publications

References 20 publications

Study of growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on nanometer‐scale patterned SiO₂/Si(001) substrates

Study of growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on nanometer‐scale patterned SiO₂/Si(001) substrates

Effect of surface energy minima on the shape of self‐induced SiGe nanoislands

Time-Dependent Capture Numbers with Repulsive Pair Interactions: Cu/Cu(111) and Ge/Si(001)

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Evolution of Ge/Si(100) islands: Island size and temperature dependence

Cited by 151 publications

References 20 publications

Study of growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on nanometer‐scale patterned SiO2/Si(001) substrates

Study of growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on nanometer‐scale patterned SiO2/Si(001) substrates

Effect of surface energy minima on the shape of self‐induced SiGe nanoislands

Time-Dependent Capture Numbers with Repulsive Pair Interactions: Cu/Cu(111) and Ge/Si(001)

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Study of growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on nanometer‐scale patterned SiO₂/Si(001) substrates

Study of growth behaviour and microstructure of epitaxially grown self‐assembled Ge quantum dots on nanometer‐scale patterned SiO₂/Si(001) substrates