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Hydrogen sensors based on electrophoretically deposited Pd nanoparticles onto InP.

Grym J, Procházková O, Yatskiv R, Piksová K - Nanoscale Res Lett (2011)

Bottom Line: Electrophoretic deposition of palladium nanoparticles prepared by the reverse micelle technique onto InP substrates is addressed.Schottky diodes based on these films show notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi level pinning.Moreover, electrical characteristics of these diodes are exceptionally sensitive to the exposure to gas mixtures with small hydrogen content.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Photonics and Electronics, Academy of Sciences CR, v,v,i,, Prague 8, Czech Republic. grym@ufe.cz.

ABSTRACT
Electrophoretic deposition of palladium nanoparticles prepared by the reverse micelle technique onto InP substrates is addressed. We demonstrate that the substrate pre-deposition treatment and the deposition conditions can extensively influence the morphology of the deposited palladium nanoparticle films. Schottky diodes based on these films show notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi level pinning. Moreover, electrical characteristics of these diodes are exceptionally sensitive to the exposure to gas mixtures with small hydrogen content.

No MeSH data available.


Related in: MedlinePlus

SEM micrographs of Pd NPs deposited at different voltages and deposition times: (a) InP-Pd-06, 30 V, 1 h; (b) InP-Pd-05, 60 V, 1 h; (c) InP-Pd-04, 100 V, 1 h; (d) InP-Pd-07, 60 V, 4 h; (e) InP-Pd-09 100 V, 18 h; and (f) InP-Pd-25, 100 V, 3 × 10 h. Magnification 60.000. The white scale bar corresponds to 100 nm. All substrates were treated in methanol before the deposition process.
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Figure 1: SEM micrographs of Pd NPs deposited at different voltages and deposition times: (a) InP-Pd-06, 30 V, 1 h; (b) InP-Pd-05, 60 V, 1 h; (c) InP-Pd-04, 100 V, 1 h; (d) InP-Pd-07, 60 V, 4 h; (e) InP-Pd-09 100 V, 18 h; and (f) InP-Pd-25, 100 V, 3 × 10 h. Magnification 60.000. The white scale bar corresponds to 100 nm. All substrates were treated in methanol before the deposition process.

Mentions: First, the influence of the applied voltage during the electrophoretic deposition on the morphology of the deposited nanolayers was investigated. When a positive potential is applied to the InP substrate, very few Pd NPs are deposited. On the contrary, when a negative potential is applied to the substrate, a full coverage of the surface may be reached (Figure 1f). It can be concluded that the reverse micelles with Pd NPs in the solution are positively charged. From now on, all the samples discussed in this article were prepared with a negative potential applied to the substrate. The influence of the magnitude of the applied voltage for the layers deposited for 1 h at 30 to 100 V is demonstrated in Figure 1a, b, c. The higher the voltage, the higher the surface coverage and the smaller the size of deposited clusters. This can be described as follows. Sarkar et al. [17] found a striking analogy between the atomic film nucleation and growth by molecular beam epitaxy and electrophoretic deposition of silica microparticles. Let us assume that the electric field-in analogy with the supersaturation in epitaxial growth-is a driving force for the deposition process of Pd NPs. In epitaxial growth, higher supersaturation leads to a higher number of critical nuclei with a smaller size. Analogously, higher applied voltages and accordingly higher electric fields result in the deposition of a high density of individual Pd NPs.


Hydrogen sensors based on electrophoretically deposited Pd nanoparticles onto InP.

Grym J, Procházková O, Yatskiv R, Piksová K - Nanoscale Res Lett (2011)

SEM micrographs of Pd NPs deposited at different voltages and deposition times: (a) InP-Pd-06, 30 V, 1 h; (b) InP-Pd-05, 60 V, 1 h; (c) InP-Pd-04, 100 V, 1 h; (d) InP-Pd-07, 60 V, 4 h; (e) InP-Pd-09 100 V, 18 h; and (f) InP-Pd-25, 100 V, 3 × 10 h. Magnification 60.000. The white scale bar corresponds to 100 nm. All substrates were treated in methanol before the deposition process.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211486&req=5

Figure 1: SEM micrographs of Pd NPs deposited at different voltages and deposition times: (a) InP-Pd-06, 30 V, 1 h; (b) InP-Pd-05, 60 V, 1 h; (c) InP-Pd-04, 100 V, 1 h; (d) InP-Pd-07, 60 V, 4 h; (e) InP-Pd-09 100 V, 18 h; and (f) InP-Pd-25, 100 V, 3 × 10 h. Magnification 60.000. The white scale bar corresponds to 100 nm. All substrates were treated in methanol before the deposition process.
Mentions: First, the influence of the applied voltage during the electrophoretic deposition on the morphology of the deposited nanolayers was investigated. When a positive potential is applied to the InP substrate, very few Pd NPs are deposited. On the contrary, when a negative potential is applied to the substrate, a full coverage of the surface may be reached (Figure 1f). It can be concluded that the reverse micelles with Pd NPs in the solution are positively charged. From now on, all the samples discussed in this article were prepared with a negative potential applied to the substrate. The influence of the magnitude of the applied voltage for the layers deposited for 1 h at 30 to 100 V is demonstrated in Figure 1a, b, c. The higher the voltage, the higher the surface coverage and the smaller the size of deposited clusters. This can be described as follows. Sarkar et al. [17] found a striking analogy between the atomic film nucleation and growth by molecular beam epitaxy and electrophoretic deposition of silica microparticles. Let us assume that the electric field-in analogy with the supersaturation in epitaxial growth-is a driving force for the deposition process of Pd NPs. In epitaxial growth, higher supersaturation leads to a higher number of critical nuclei with a smaller size. Analogously, higher applied voltages and accordingly higher electric fields result in the deposition of a high density of individual Pd NPs.

Bottom Line: Electrophoretic deposition of palladium nanoparticles prepared by the reverse micelle technique onto InP substrates is addressed.Schottky diodes based on these films show notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi level pinning.Moreover, electrical characteristics of these diodes are exceptionally sensitive to the exposure to gas mixtures with small hydrogen content.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Photonics and Electronics, Academy of Sciences CR, v,v,i,, Prague 8, Czech Republic. grym@ufe.cz.

ABSTRACT
Electrophoretic deposition of palladium nanoparticles prepared by the reverse micelle technique onto InP substrates is addressed. We demonstrate that the substrate pre-deposition treatment and the deposition conditions can extensively influence the morphology of the deposited palladium nanoparticle films. Schottky diodes based on these films show notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi level pinning. Moreover, electrical characteristics of these diodes are exceptionally sensitive to the exposure to gas mixtures with small hydrogen content.

No MeSH data available.


Related in: MedlinePlus