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Optimal Growth Conditions for Selective Ge Islands Positioning on Pit-Patterned Si(001).

Bergamaschini R, Montalenti F, Miglio L - Nanoscale Res Lett (2010)

Bottom Line: The method allows us to explore long time-scale evolution while using large simulation cells.We analyze the possibility to achieve selective nucleation and island homogeneity as a function of the various parameters (flux, temperature, pit period) able to influence the growth process.The presence of an optimal condition where the atomic diffusivity is sufficient to guarantee nucleation only within pits, but not so large to induce significant Ostwald ripening, is clearly demonstrated.

View Article: PubMed Central - HTML - PubMed

Affiliation: L-NESS and Materials Science Department, University of Milano-Bicocca, Via R. Cozzi 53, 20125 Milano, Italy.

ABSTRACT
We investigate ordered nucleation of Ge islands on pit-patterned Si(001) using an original hybrid Kinetic Monte Carlo model. The method allows us to explore long time-scale evolution while using large simulation cells. We analyze the possibility to achieve selective nucleation and island homogeneity as a function of the various parameters (flux, temperature, pit period) able to influence the growth process. The presence of an optimal condition where the atomic diffusivity is sufficient to guarantee nucleation only within pits, but not so large to induce significant Ostwald ripening, is clearly demonstrated.

No MeSH data available.


Related in: MedlinePlus

Islands volume distributions from simulations at different temperatures (750, 850 and 950 K for the simulation parameters) at fixed flux (0.02 ML/s) and pit spacing (40 nm) after deposition of 1 ML of Ge. Curves are normalized and volumes are scaled with respect to the mean; values are averaged from 5 independent simulations. At the lowest temperature, the distribution is bimodal: the peak at larger volume is for islands inside pits, while the other refers to those grown in between.
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Figure 3: Islands volume distributions from simulations at different temperatures (750, 850 and 950 K for the simulation parameters) at fixed flux (0.02 ML/s) and pit spacing (40 nm) after deposition of 1 ML of Ge. Curves are normalized and volumes are scaled with respect to the mean; values are averaged from 5 independent simulations. At the lowest temperature, the distribution is bimodal: the peak at larger volume is for islands inside pits, while the other refers to those grown in between.

Mentions: In accordance with previous studies based on standard KMC approaches [19,20], our simulations show the existence of an optimal range of parameters enabling both positional and size ordering in the islands grown on the patterned substrate. Figure 2 shows some snapshots taken from our simulations at different temperature, deposition flux and pit spacing. From a more quantitative point of view, the size uniformity of islands inside the pits as a function of the growth temperature can be established through the distributions shown in Fig. 3. The shown results are referred to the deposition of 1 ML of Ge. As already stressed in the previous Section, we assume that a critical (∼4 ML [25]) WL is already present, so that our results are representative of a true coverage of ∼5 ML.


Optimal Growth Conditions for Selective Ge Islands Positioning on Pit-Patterned Si(001).

Bergamaschini R, Montalenti F, Miglio L - Nanoscale Res Lett (2010)

Islands volume distributions from simulations at different temperatures (750, 850 and 950 K for the simulation parameters) at fixed flux (0.02 ML/s) and pit spacing (40 nm) after deposition of 1 ML of Ge. Curves are normalized and volumes are scaled with respect to the mean; values are averaged from 5 independent simulations. At the lowest temperature, the distribution is bimodal: the peak at larger volume is for islands inside pits, while the other refers to those grown in between.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2991238&req=5

Figure 3: Islands volume distributions from simulations at different temperatures (750, 850 and 950 K for the simulation parameters) at fixed flux (0.02 ML/s) and pit spacing (40 nm) after deposition of 1 ML of Ge. Curves are normalized and volumes are scaled with respect to the mean; values are averaged from 5 independent simulations. At the lowest temperature, the distribution is bimodal: the peak at larger volume is for islands inside pits, while the other refers to those grown in between.
Mentions: In accordance with previous studies based on standard KMC approaches [19,20], our simulations show the existence of an optimal range of parameters enabling both positional and size ordering in the islands grown on the patterned substrate. Figure 2 shows some snapshots taken from our simulations at different temperature, deposition flux and pit spacing. From a more quantitative point of view, the size uniformity of islands inside the pits as a function of the growth temperature can be established through the distributions shown in Fig. 3. The shown results are referred to the deposition of 1 ML of Ge. As already stressed in the previous Section, we assume that a critical (∼4 ML [25]) WL is already present, so that our results are representative of a true coverage of ∼5 ML.

Bottom Line: The method allows us to explore long time-scale evolution while using large simulation cells.We analyze the possibility to achieve selective nucleation and island homogeneity as a function of the various parameters (flux, temperature, pit period) able to influence the growth process.The presence of an optimal condition where the atomic diffusivity is sufficient to guarantee nucleation only within pits, but not so large to induce significant Ostwald ripening, is clearly demonstrated.

View Article: PubMed Central - HTML - PubMed

Affiliation: L-NESS and Materials Science Department, University of Milano-Bicocca, Via R. Cozzi 53, 20125 Milano, Italy.

ABSTRACT
We investigate ordered nucleation of Ge islands on pit-patterned Si(001) using an original hybrid Kinetic Monte Carlo model. The method allows us to explore long time-scale evolution while using large simulation cells. We analyze the possibility to achieve selective nucleation and island homogeneity as a function of the various parameters (flux, temperature, pit period) able to influence the growth process. The presence of an optimal condition where the atomic diffusivity is sufficient to guarantee nucleation only within pits, but not so large to induce significant Ostwald ripening, is clearly demonstrated.

No MeSH data available.


Related in: MedlinePlus