Limits...
Relationship between structural changes, hydrogen content and annealing in stacks of ultrathin Si/Ge amorphous layers.

Frigeri C, Serényi M, Khánh NQ, Csik A, Riesz F, Erdélyi Z, Nasi L, Beke DL, Boyen HG - Nanoscale Res Lett (2011)

Bottom Line: Hydrogenated multilayers (MLs) of a-Si/a-Ge have been analysed to establish the reasons of H release during annealing that has been seen to bring about structural modifications even up to well-detectable surface degradation.Analyses carried out on single layers of a-Si and a-Ge show that H is released from its bond to the host lattice atom and that it escapes from the layer much more efficiently in a-Ge than in a-Si because of the smaller binding energy of the H-Ge bond and probably of a greater weakness of the Ge lattice.This should support the previous hypothesis that the structural degradation of a-Si/a-Ge MLs primary starts with the formation of H bubbles in the Ge layers.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNR-IMEM Institute, Parco Area delle Scienze 37/A, 43100 Parma, Italy. frigeri@imem.cnr.it.

ABSTRACT
Hydrogenated multilayers (MLs) of a-Si/a-Ge have been analysed to establish the reasons of H release during annealing that has been seen to bring about structural modifications even up to well-detectable surface degradation. Analyses carried out on single layers of a-Si and a-Ge show that H is released from its bond to the host lattice atom and that it escapes from the layer much more efficiently in a-Ge than in a-Si because of the smaller binding energy of the H-Ge bond and probably of a greater weakness of the Ge lattice. This should support the previous hypothesis that the structural degradation of a-Si/a-Ge MLs primary starts with the formation of H bubbles in the Ge layers.

No MeSH data available.


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Bumps height (dash blue line) and size (solid black line) as a function of the H flow rate in a-Si/a-Ge ML samples annealed at 350°C for 10 h.
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Figure 1: Bumps height (dash blue line) and size (solid black line) as a function of the H flow rate in a-Si/a-Ge ML samples annealed at 350°C for 10 h.

Mentions: Previous studies have shown that the hydrogen content and annealing conditions can dramatically influence the structural stability of the a-Si/a-Ge multilayers (MLs) produced by sputtering and then annealed to produce intermixing [7-9]. It was reported that surface bumps formed, size and height of which increased with increasing H content and/or annealing temperature and time [7-9] (see Figure 1). Craters also formed subsequent to the explosion of the bumps. The bumps were ascribed to the formation of bubbles of hydrogen in the MLs [7,8]. The formation of H bubbles was also suggested by Acco et al. [10] in single layers of a-Si. It was hypothesized that H could be first released from the Ge layers because of the lower binding energy of the Ge-H bond with respect to the Si-H one [7,8]. To check this hypothesis, the MLs were additionally investigated by IR absorbance and an analysis of the structural behaviour of single films of a-Si and a-Ge, submitted to the same annealing as for the MLs previously studied, was performed. The results are reported in this article.


Relationship between structural changes, hydrogen content and annealing in stacks of ultrathin Si/Ge amorphous layers.

Frigeri C, Serényi M, Khánh NQ, Csik A, Riesz F, Erdélyi Z, Nasi L, Beke DL, Boyen HG - Nanoscale Res Lett (2011)

Bumps height (dash blue line) and size (solid black line) as a function of the H flow rate in a-Si/a-Ge ML samples annealed at 350°C for 10 h.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211242&req=5

Figure 1: Bumps height (dash blue line) and size (solid black line) as a function of the H flow rate in a-Si/a-Ge ML samples annealed at 350°C for 10 h.
Mentions: Previous studies have shown that the hydrogen content and annealing conditions can dramatically influence the structural stability of the a-Si/a-Ge multilayers (MLs) produced by sputtering and then annealed to produce intermixing [7-9]. It was reported that surface bumps formed, size and height of which increased with increasing H content and/or annealing temperature and time [7-9] (see Figure 1). Craters also formed subsequent to the explosion of the bumps. The bumps were ascribed to the formation of bubbles of hydrogen in the MLs [7,8]. The formation of H bubbles was also suggested by Acco et al. [10] in single layers of a-Si. It was hypothesized that H could be first released from the Ge layers because of the lower binding energy of the Ge-H bond with respect to the Si-H one [7,8]. To check this hypothesis, the MLs were additionally investigated by IR absorbance and an analysis of the structural behaviour of single films of a-Si and a-Ge, submitted to the same annealing as for the MLs previously studied, was performed. The results are reported in this article.

Bottom Line: Hydrogenated multilayers (MLs) of a-Si/a-Ge have been analysed to establish the reasons of H release during annealing that has been seen to bring about structural modifications even up to well-detectable surface degradation.Analyses carried out on single layers of a-Si and a-Ge show that H is released from its bond to the host lattice atom and that it escapes from the layer much more efficiently in a-Ge than in a-Si because of the smaller binding energy of the H-Ge bond and probably of a greater weakness of the Ge lattice.This should support the previous hypothesis that the structural degradation of a-Si/a-Ge MLs primary starts with the formation of H bubbles in the Ge layers.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNR-IMEM Institute, Parco Area delle Scienze 37/A, 43100 Parma, Italy. frigeri@imem.cnr.it.

ABSTRACT
Hydrogenated multilayers (MLs) of a-Si/a-Ge have been analysed to establish the reasons of H release during annealing that has been seen to bring about structural modifications even up to well-detectable surface degradation. Analyses carried out on single layers of a-Si and a-Ge show that H is released from its bond to the host lattice atom and that it escapes from the layer much more efficiently in a-Ge than in a-Si because of the smaller binding energy of the H-Ge bond and probably of a greater weakness of the Ge lattice. This should support the previous hypothesis that the structural degradation of a-Si/a-Ge MLs primary starts with the formation of H bubbles in the Ge layers.

No MeSH data available.


Related in: MedlinePlus