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New Si-based multilayers for solar cell applications.

Nalini RP, Dufour C, Cardin J, Gourbilleau F - Nanoscale Res Lett (2011)

Bottom Line: The comparison between SiO2 and SiNx host matrices in the optical properties of the multilayers is detailed.The effect of specific annealing treatments on the optical properties is studied and we report a higher visible luminescence with a control over the thermal budget when SiO2 is replaced by the SiNx matrix.The latter seems to be a potential candidate to replace the most sought SiO2 host matrix.

View Article: PubMed Central - HTML - PubMed

Affiliation: CIMAP UMR CNRS/CEA/ENSICAEN/UCBN, 6 Bd, Maréchal Juin, 14050 Caen Cedex 4, France. fabrice.gourbilleau@ensicaen.fr.

ABSTRACT
In this article, we have fabricated and studied a new multilayer structure Si-SiO2/SiNx by reactive magnetron sputtering. The comparison between SiO2 and SiNx host matrices in the optical properties of the multilayers is detailed. Structural analysis was made on the multilayer structures using Fourier transform infrared spectroscopy. The effect of specific annealing treatments on the optical properties is studied and we report a higher visible luminescence with a control over the thermal budget when SiO2 is replaced by the SiNx matrix. The latter seems to be a potential candidate to replace the most sought SiO2 host matrix.

No MeSH data available.


Effect of sublayer thickness and total thickness of SiNx on the PL spectrum on RTA. (Inset: comparison between the SRSO/SiO2 annealed at 1 h-1100°C and SRSO/SiNx structure subjected to RTA).
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Figure 3: Effect of sublayer thickness and total thickness of SiNx on the PL spectrum on RTA. (Inset: comparison between the SRSO/SiO2 annealed at 1 h-1100°C and SRSO/SiNx structure subjected to RTA).

Mentions: It can be noticed from the spectrum that when the multilayers are subjected to the classical annealing treatment of 1 h-1100°C, there is no emission from the SRSO/SiNx while the SRSO/SiO2 structure shows a strong PL signal and has a wide range of emission spectrum. At the same time, it is interesting to note a very weak PL signal in the case of SiNx/SiO2. The PL peaks appear in a region usually related to the optical transitions in the SiO2 matrix due to the presence of defects [3,17]. The lower part of Figure 2 shows the PL spectrum recorded after annealing the multilayer structures for 1 min at 1000°C (RTA). The response of the multilayers to this annealing treatment shows almost a reversed trend of what was observed in the case of classical annealing treatment. It can be noted that the SRSO/SiNx has the highest intensity. No PL emission has been recorded from the SRSO/SiO2 system. We may note from the figures that the luminescence peak arising from the SiNx/SiO2 structure around 1.9 eV is the same whatever the annealing temperature. The fitting of the PL curve recorded from the SRSO/SiNx film evidences the presence of two emission bands centered at 1.65 and 1.37 eV. Though this result is interesting and shows the possibility of exploiting SRSO alternated with the SiNx sublayer to achieve a control over the thermal budget, it also has to be mentioned that the PL intensity obtained is one order of magnitude lower than the emission of SRSO/SiO2 subjected to classical annealing. Hence, two methods of fabrication were attempted with the aim of increasing the PL intensity: (i) increasing the SiNx sublayer thickness to 5 nm and (ii) doubling the number of periods, i.e., fabricating 100 periods of 3.5 nm SRSO alternated with 5 nm SiNx. Figure 3 shows the effect of the aforesaid fabrication methods on the PL spectrum of the SRSO/SiNx multilayers. All the spectra have been normalized to 100 nm thickness for comparison. The interference effect in PL intensity has been also investigated by the previously mentioned method PL intensity from both 50 periods multilayers should be decreased by about 15%, in order to take into account the enhancement effect due to maxima of interference. The first method adopted reveals that the SiNx thickness has some significant contribution toward the luminescence. There is a slight change in the emission wavelength from 1.59 eV with 3.5 nm SiNx sublayer to 1.55 eV in the case of 5 nm SiNx sublayer. Irrespective of the number of periods deposited, for a given sublayer thickness the wavelength of emission peak remained constant. It is interesting to note that the emission intensity increases with the SiNx thickness. This result motivated toward trying out the second method mentioned and it can be noticed that the PL signal increases 7.4 times when the number of (3.5 nm)SRSO/(5 nm)SiNx pattern is increased from 50 to 100. For that case one can notice is the presence of a small peak between 1.90 and 1.65 eV and another one around 1.5 eV. The inset in Figure 3 shows a comparison between the SRSO/SiO2 annealed at 1 h-1100°C and SRSO/SiNx structure subjected to RTA. One can notice that the emission peak from the SRSO/SiNx system shifts in the visible region and this is one of the advantageous aspects for the solar cell application. It is very interesting to note that the SRSO/SiNx annealed for a very short time of 1 min at 1000°C is 1.43 times more intense than the SRSO/SiO2 structure annealed for a long time of 1 h and at higher temperature. Accounting for the interference effect, we can infer that SRSO/SiNx exhibits higher PL intensity than SRSO/SiO2. Thus, it can be seen that a replacement of the SiO2 sublayer by the SiNx sublayer and alternating it with the SRSO sublayer not only favors luminescence but paves way to achieve a control over the thermal budget.


New Si-based multilayers for solar cell applications.

Nalini RP, Dufour C, Cardin J, Gourbilleau F - Nanoscale Res Lett (2011)

Effect of sublayer thickness and total thickness of SiNx on the PL spectrum on RTA. (Inset: comparison between the SRSO/SiO2 annealed at 1 h-1100°C and SRSO/SiNx structure subjected to RTA).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211207&req=5

Figure 3: Effect of sublayer thickness and total thickness of SiNx on the PL spectrum on RTA. (Inset: comparison between the SRSO/SiO2 annealed at 1 h-1100°C and SRSO/SiNx structure subjected to RTA).
Mentions: It can be noticed from the spectrum that when the multilayers are subjected to the classical annealing treatment of 1 h-1100°C, there is no emission from the SRSO/SiNx while the SRSO/SiO2 structure shows a strong PL signal and has a wide range of emission spectrum. At the same time, it is interesting to note a very weak PL signal in the case of SiNx/SiO2. The PL peaks appear in a region usually related to the optical transitions in the SiO2 matrix due to the presence of defects [3,17]. The lower part of Figure 2 shows the PL spectrum recorded after annealing the multilayer structures for 1 min at 1000°C (RTA). The response of the multilayers to this annealing treatment shows almost a reversed trend of what was observed in the case of classical annealing treatment. It can be noted that the SRSO/SiNx has the highest intensity. No PL emission has been recorded from the SRSO/SiO2 system. We may note from the figures that the luminescence peak arising from the SiNx/SiO2 structure around 1.9 eV is the same whatever the annealing temperature. The fitting of the PL curve recorded from the SRSO/SiNx film evidences the presence of two emission bands centered at 1.65 and 1.37 eV. Though this result is interesting and shows the possibility of exploiting SRSO alternated with the SiNx sublayer to achieve a control over the thermal budget, it also has to be mentioned that the PL intensity obtained is one order of magnitude lower than the emission of SRSO/SiO2 subjected to classical annealing. Hence, two methods of fabrication were attempted with the aim of increasing the PL intensity: (i) increasing the SiNx sublayer thickness to 5 nm and (ii) doubling the number of periods, i.e., fabricating 100 periods of 3.5 nm SRSO alternated with 5 nm SiNx. Figure 3 shows the effect of the aforesaid fabrication methods on the PL spectrum of the SRSO/SiNx multilayers. All the spectra have been normalized to 100 nm thickness for comparison. The interference effect in PL intensity has been also investigated by the previously mentioned method PL intensity from both 50 periods multilayers should be decreased by about 15%, in order to take into account the enhancement effect due to maxima of interference. The first method adopted reveals that the SiNx thickness has some significant contribution toward the luminescence. There is a slight change in the emission wavelength from 1.59 eV with 3.5 nm SiNx sublayer to 1.55 eV in the case of 5 nm SiNx sublayer. Irrespective of the number of periods deposited, for a given sublayer thickness the wavelength of emission peak remained constant. It is interesting to note that the emission intensity increases with the SiNx thickness. This result motivated toward trying out the second method mentioned and it can be noticed that the PL signal increases 7.4 times when the number of (3.5 nm)SRSO/(5 nm)SiNx pattern is increased from 50 to 100. For that case one can notice is the presence of a small peak between 1.90 and 1.65 eV and another one around 1.5 eV. The inset in Figure 3 shows a comparison between the SRSO/SiO2 annealed at 1 h-1100°C and SRSO/SiNx structure subjected to RTA. One can notice that the emission peak from the SRSO/SiNx system shifts in the visible region and this is one of the advantageous aspects for the solar cell application. It is very interesting to note that the SRSO/SiNx annealed for a very short time of 1 min at 1000°C is 1.43 times more intense than the SRSO/SiO2 structure annealed for a long time of 1 h and at higher temperature. Accounting for the interference effect, we can infer that SRSO/SiNx exhibits higher PL intensity than SRSO/SiO2. Thus, it can be seen that a replacement of the SiO2 sublayer by the SiNx sublayer and alternating it with the SRSO sublayer not only favors luminescence but paves way to achieve a control over the thermal budget.

Bottom Line: The comparison between SiO2 and SiNx host matrices in the optical properties of the multilayers is detailed.The effect of specific annealing treatments on the optical properties is studied and we report a higher visible luminescence with a control over the thermal budget when SiO2 is replaced by the SiNx matrix.The latter seems to be a potential candidate to replace the most sought SiO2 host matrix.

View Article: PubMed Central - HTML - PubMed

Affiliation: CIMAP UMR CNRS/CEA/ENSICAEN/UCBN, 6 Bd, Maréchal Juin, 14050 Caen Cedex 4, France. fabrice.gourbilleau@ensicaen.fr.

ABSTRACT
In this article, we have fabricated and studied a new multilayer structure Si-SiO2/SiNx by reactive magnetron sputtering. The comparison between SiO2 and SiNx host matrices in the optical properties of the multilayers is detailed. Structural analysis was made on the multilayer structures using Fourier transform infrared spectroscopy. The effect of specific annealing treatments on the optical properties is studied and we report a higher visible luminescence with a control over the thermal budget when SiO2 is replaced by the SiNx matrix. The latter seems to be a potential candidate to replace the most sought SiO2 host matrix.

No MeSH data available.