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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.


Related in: MedlinePlus

Calibration of H incorporation with ERDA. (a) 1.6 MeV 4He+ ERDA spectra of H in the a-Si single layers hydrogenated at flow rates of 0.4, 0.8 and 1.5 ml/min (#4, #8 and #15, respectively, in the plot). (b) Total H concentration in a-Si (solid black line) and a-Ge (dash blue line) layers as a function of the H flow rate as determined by ERDA.
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Figure 2: Calibration of H incorporation with ERDA. (a) 1.6 MeV 4He+ ERDA spectra of H in the a-Si single layers hydrogenated at flow rates of 0.4, 0.8 and 1.5 ml/min (#4, #8 and #15, respectively, in the plot). (b) Total H concentration in a-Si (solid black line) and a-Ge (dash blue line) layers as a function of the H flow rate as determined by ERDA.

Mentions: The calibration of the sputtering apparatus as regards the incorporation of H was done using ERDA by means of the single layers of a-Si and a-Ge. Figure 2a shows the ERDA spectra for the non-annealed a-Si layers hydrogenated at different flow rates. The signal of the recoiled H atoms from the sample surface locates at channel 120. Behind the surface, the distribution of H seems to be reasonably homogeneous in the whole layer. Small peaks at channels 97 and 120 can be associated with the contamination at the surface either of the deposited layer or of the substrate. The tail behind the H peak is due to the multiple scattering, which the RBX code is not yet able to simulate. Similar spectra were obtained for a-Ge. By using the simulation program of ref. [11], the calibration curves of Figure 2b giving the incorporated at.% of H as a function of the H flow rate were obtained. The increase in H concentration in a-Si already tends to slow down significantly between 1 and 1.5 ml/min flow rate (0.78 and 1.46% partial of total pressure), reaching a maximum value of 17 at.%. In a-Ge, the same slowing down trend is observed for the same flow rate values reaching a maximum value of only about 7 at.% (Figure 2b).


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)

Calibration of H incorporation with ERDA. (a) 1.6 MeV 4He+ ERDA spectra of H in the a-Si single layers hydrogenated at flow rates of 0.4, 0.8 and 1.5 ml/min (#4, #8 and #15, respectively, in the plot). (b) Total H concentration in a-Si (solid black line) and a-Ge (dash blue line) layers as a function of the H flow rate as determined by ERDA.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Calibration of H incorporation with ERDA. (a) 1.6 MeV 4He+ ERDA spectra of H in the a-Si single layers hydrogenated at flow rates of 0.4, 0.8 and 1.5 ml/min (#4, #8 and #15, respectively, in the plot). (b) Total H concentration in a-Si (solid black line) and a-Ge (dash blue line) layers as a function of the H flow rate as determined by ERDA.
Mentions: The calibration of the sputtering apparatus as regards the incorporation of H was done using ERDA by means of the single layers of a-Si and a-Ge. Figure 2a shows the ERDA spectra for the non-annealed a-Si layers hydrogenated at different flow rates. The signal of the recoiled H atoms from the sample surface locates at channel 120. Behind the surface, the distribution of H seems to be reasonably homogeneous in the whole layer. Small peaks at channels 97 and 120 can be associated with the contamination at the surface either of the deposited layer or of the substrate. The tail behind the H peak is due to the multiple scattering, which the RBX code is not yet able to simulate. Similar spectra were obtained for a-Ge. By using the simulation program of ref. [11], the calibration curves of Figure 2b giving the incorporated at.% of H as a function of the H flow rate were obtained. The increase in H concentration in a-Si already tends to slow down significantly between 1 and 1.5 ml/min flow rate (0.78 and 1.46% partial of total pressure), reaching a maximum value of 17 at.%. In a-Ge, the same slowing down trend is observed for the same flow rate values reaching a maximum value of only about 7 at.% (Figure 2b).

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