Effect of the growth rate on the morphology and structural properties of hut-shaped Ge islands in Si(001)

Yakimov, A. I.; Nikiforov, A. I.; Двуреченский, А. В.; Ulyanov, Vladimir V.; Володин, В. А.; Groetzschel, R.

doi:10.1088/0957-4484/17/18/036

Cited by 27 publications

(10 citation statements)

References 29 publications

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“…39 The average Ge content of 80%-90% ͑depending on t Si ͒ in the nanoclusters was determined from Raman measurements. The transition from two-dimensional to three-dimensional island growth was observed after ϳ4 monolayers ͑ 1 ML= 1.41 Å͒ of Ge deposition both for the first and second Ge layers.…”

Section: Methodsmentioning

confidence: 99%

Hole states in Ge∕Si quantum-dot molecules produced by strain-driven self-assembly

Yakimov

Mikhalyov

Двуреченский

et al. 2007

Journal of Applied Physics

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Space-charge spectroscopy was employed to study hole emission from the confined states in vertically self-aligned double Ge quantum dots separated by a Si barrier. From the temperature- and frequency-dependent measurements, the hole binding energy was determined as a function of the separation between the dots, tSi. Increasing of the ground state hole energy due to formation of a bonding molecular orbital was found to be as large as ∼50meV at tSi=1.5nm. For a dot layer separation exceeding 3nm, the hole binding energy in double-dot molecule becomes smaller than the ionization energy of the single Ge dot, contrasting with a simplified quantum-mechanical molecular model. To analyze the experiment the electronic structure of two vertically coupled pyramidal Ge quantum dots embedded in Si was investigated by a nearest neighbor tight-binding single-particle Hamiltonian with the sp3 basis. The elastic strain due to the lattice mismatch between Ge and Si was included into the problem. The three-dimensional spatial strain distribution was found in terms of atomic positions using a valence-force-field theory with a Keating interatomic potential. It was demonstrated that formation of single-particle hole states in self-organized molecules is governed by the interplay among two effects. The first is the quantum-mechanical coupling between the individual states of two dots constituting the molecule. The second one originates from asymmetry of the strain field distribution within the top and bottom dots due to the lack of inversion symmetry with respect to the medium plane between the dots. Analysis of the biaxial strain distribution showed that anomalous decreasing of the hole binding energy below the value of the single dot with increasing interdot separation is caused by the partial strain relaxation upon dot stacking accompanied by the strain-induced reduction of the hole confinement potential. We found that the molecule-type hole state delocalized fairly over the two dots is formed only at tSi<3.3nm and at tSi>3.8nm. For the intermediate distances (3.3nm⩽tSi⩽3.8nm), the hole becomes confined mostly inside the bottom, most strained Ge dot. The overall agreement between theory and experiment turns out to be quite good, indicating the crucial role played by strain fields in electronic coupling of self-assembled quantum-dot molecules.

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Section: Methodsmentioning

confidence: 99%

Hole states in Ge∕Si quantum-dot molecules produced by strain-driven self-assembly

Yakimov

Mikhalyov

Двуреченский

et al. 2007

Journal of Applied Physics

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“…For our experimental conditions the parameter B = 2 [2,3]. The presence of Ge-Si bonds on QD interface can be taken into account by the way described in [3,4].…”

Section: Resultsmentioning

confidence: 99%

“…The presence of Ge-Si bonds on QD interface can be taken into account by the way described in [3,4]. If the quantity of deposited Ge in monolayers m is exactly known, one can apply the approach used in work [3]. Then:…”

Section: Resultsmentioning

confidence: 99%

Raman scattering diagnostics of as grown and pulsed laser modified Ge-Si nanostructures with quantum dots

Gatskevich¹,

Ивлев²,

Володин

et al. 2007

SPIE Proceedings

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“…Another feature at ∼420 cm −1 corresponds to the local Ge-Si vibrations. Based on Raman measurements the Ge-Si intermixing effect can be found from the ratio of the integrated intensities of the Ge-Ge and Ge-Si peaks 57 I Ge-Ge…”

Section: Effect Of Growth Rate On Germanium Hut Clustersmentioning

confidence: 99%

Germanium Self-Assembled Quantum Dots in Silicon for Nano- and Optoelectronics

Yakimov¹,

Двуреченский²,

Никифоров³

2006

Journal of Nanoelectronics and Optoelectronics

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The scope of this article is to review the formation mechanisms, variety of electronic and optical phenomena, as well as possible device-oriented applications, in Ge/Si self-assembled quantum dots that have been synthesized by molecular-beam heteroepitaxy. A difference of this review from the other existing works on physics of Ge/Si nanostructures is that we will focus on the fundamental aspects and device applications of the dots whose size is extremely small (∼10 nm) and the electronic states resemble certainly those of an atom even at room temperature.

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Effect of the growth rate on the morphology and structural properties of hut-shaped Ge islands in Si(001)

Cited by 27 publications

References 29 publications

Hole states in Ge∕Si quantum-dot molecules produced by strain-driven self-assembly

Hole states in Ge∕Si quantum-dot molecules produced by strain-driven self-assembly

Raman scattering diagnostics of as grown and pulsed laser modified Ge-Si nanostructures with quantum dots

Germanium Self-Assembled Quantum Dots in Silicon for Nano- and Optoelectronics

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