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Plasmon-Enhanced Surface Photovoltage of ZnO/Ag Nanogratings.

Gwon M, Sohn A, Cho Y, Phark SH, Ko J, Sang Kim Y, Kim DW - Sci Rep (2015)

Bottom Line: SPP excitation influenced the spatial distribution of the photo-excited carriers and their recombination processes.As a result, the SPV relaxation time clearly depended on the wavelength and polarization of the incident light.All of these results suggested that SPV measurement using KPFM should be very useful for studying the plasmonic effects in nanoscale metal/semiconductor hybrid structures.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Ewha Womans University, Seoul 120750, Korea.

ABSTRACT
We investigated the surface photovoltage (SPV) behaviors of ZnO/Ag one-dimensional (1D) nanogratings using Kelvin probe force microscopy (KPFM). The grating structure could couple surface plasmon polaritons (SPPs) with photons, giving rise to strong light confinement at the ZnO/Ag interface. The larger field produced more photo-excited carriers and increased the SPV. SPP excitation influenced the spatial distribution of the photo-excited carriers and their recombination processes. As a result, the SPV relaxation time clearly depended on the wavelength and polarization of the incident light. All of these results suggested that SPV measurement using KPFM should be very useful for studying the plasmonic effects in nanoscale metal/semiconductor hybrid structures.

No MeSH data available.


SPV of the ZnO/Ag flat thin film and nanograting samples under illumination with red and green light with TM- and TE-mode polarizations.
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f4: SPV of the ZnO/Ag flat thin film and nanograting samples under illumination with red and green light with TM- and TE-mode polarizations.

Mentions: Figure 4 shows the SPV values obtained from a ZnO/Ag thin film and the ZnO/Ag nanograting, when the red and green light was illuminated with TM- and TE-mode polarizations. The SPV value could be estimated at each pixel of the WS maps (for the nanograting, see Fig. 2a–f). The average data and the statistical distributions are shown in Fig. 4. The SPV values of the thin film and the nanograting under the green light are larger than those under the red light. Such wavelength dependence is determined by the trap state energy distribution of ZnO thin films25. Under the green light with TM mode, the SPV of ZnO/Ag is the largest (~60 meV) among all of the measured SPV values. In contrast, the polarization dependence of the flat thin film is not very notable. Also, it can be noted that the SPV under the red light hardly depends on the polarization of the incoming light for both the thin film and nanograting samples. The excitation of SPP via light is not very efficient in flat samples, since the momentum of the SPP mode is greater than that of a free-space photon of the same frequency14. In the nanograting, such momentum mismatch can be overcome and SPP with the specific energy range from 2 eV to 3 eV can be excited in our ZnO/Ag nanograting samples (see Figure S1). Thus red light with a wavelength of 635 nm (1.95 eV) could not excite SPP, but green light with a wavelength of 532 nm (2.33 eV) could. The wavelength and polarization dependence of SPV may suggest that the interaction between SPPs at the ZnO/Ag interface and charge carriers in the ZnO layer could affect the SPV behaviors of our ZnO/Ag nanogratings.


Plasmon-Enhanced Surface Photovoltage of ZnO/Ag Nanogratings.

Gwon M, Sohn A, Cho Y, Phark SH, Ko J, Sang Kim Y, Kim DW - Sci Rep (2015)

SPV of the ZnO/Ag flat thin film and nanograting samples under illumination with red and green light with TM- and TE-mode polarizations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645158&req=5

f4: SPV of the ZnO/Ag flat thin film and nanograting samples under illumination with red and green light with TM- and TE-mode polarizations.
Mentions: Figure 4 shows the SPV values obtained from a ZnO/Ag thin film and the ZnO/Ag nanograting, when the red and green light was illuminated with TM- and TE-mode polarizations. The SPV value could be estimated at each pixel of the WS maps (for the nanograting, see Fig. 2a–f). The average data and the statistical distributions are shown in Fig. 4. The SPV values of the thin film and the nanograting under the green light are larger than those under the red light. Such wavelength dependence is determined by the trap state energy distribution of ZnO thin films25. Under the green light with TM mode, the SPV of ZnO/Ag is the largest (~60 meV) among all of the measured SPV values. In contrast, the polarization dependence of the flat thin film is not very notable. Also, it can be noted that the SPV under the red light hardly depends on the polarization of the incoming light for both the thin film and nanograting samples. The excitation of SPP via light is not very efficient in flat samples, since the momentum of the SPP mode is greater than that of a free-space photon of the same frequency14. In the nanograting, such momentum mismatch can be overcome and SPP with the specific energy range from 2 eV to 3 eV can be excited in our ZnO/Ag nanograting samples (see Figure S1). Thus red light with a wavelength of 635 nm (1.95 eV) could not excite SPP, but green light with a wavelength of 532 nm (2.33 eV) could. The wavelength and polarization dependence of SPV may suggest that the interaction between SPPs at the ZnO/Ag interface and charge carriers in the ZnO layer could affect the SPV behaviors of our ZnO/Ag nanogratings.

Bottom Line: SPP excitation influenced the spatial distribution of the photo-excited carriers and their recombination processes.As a result, the SPV relaxation time clearly depended on the wavelength and polarization of the incident light.All of these results suggested that SPV measurement using KPFM should be very useful for studying the plasmonic effects in nanoscale metal/semiconductor hybrid structures.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Ewha Womans University, Seoul 120750, Korea.

ABSTRACT
We investigated the surface photovoltage (SPV) behaviors of ZnO/Ag one-dimensional (1D) nanogratings using Kelvin probe force microscopy (KPFM). The grating structure could couple surface plasmon polaritons (SPPs) with photons, giving rise to strong light confinement at the ZnO/Ag interface. The larger field produced more photo-excited carriers and increased the SPV. SPP excitation influenced the spatial distribution of the photo-excited carriers and their recombination processes. As a result, the SPV relaxation time clearly depended on the wavelength and polarization of the incident light. All of these results suggested that SPV measurement using KPFM should be very useful for studying the plasmonic effects in nanoscale metal/semiconductor hybrid structures.

No MeSH data available.