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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.


(a) Low- and (b) high-magnification cross-sectional scanning electron microscope images and (c) a schematic of a ZnO/Ag grating structure. (d) Schematic of the KPFM measurement setup in the glove box.
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f1: (a) Low- and (b) high-magnification cross-sectional scanning electron microscope images and (c) a schematic of a ZnO/Ag grating structure. (d) Schematic of the KPFM measurement setup in the glove box.

Mentions: One-dimensional (1D) ZnO/Ag nanograting structures, with a period of 1 μm and a line-to-space ratio of 1:1, were prepared on polymer patterns, fabricated by imprint lithography, as shown in Fig. 1a–c. 100-nm-thick ZnO and 100-nm-thick Ag thin films were deposited on the nanopatterns at room temperature. For comparison, ZnO/Ag thin films were also prepared on flat Si wafers. Details of the sample fabrication procedures are available elsewhere14 and the Methods section. Because of the limited step coverage, the thickness of the both ZnO and Ag thin films at the sidewalls of the nanograting was only 38 nm, as shown in the scanning electron microscopy image (Fig. 1b) and the schematic of the nanograting (Fig. 1c). Figure 1d shows a schematic of our KPFM measurement system (XE-100, Park Systems) in a glove box filled with N2 gas. We used 5 mW green and red laser modules with wavelengths of 532 nm and 635 nm (LDC series, Korea), respectively, for the SPV measurements. The light was aligned to illuminate the sample area under the KPFM tip with an incident angle of 65°. At smaller angles, part of the laser light was blocked by the KPFM head. Depending on the incident angle, the energy of light-coupled SPP mode can be determined by the SPP dispersion relation (see Figure S1). The polarization of the laser light was adjusted with a linear polarizer to either transverse electric (TE) or transverse magnetic (TM) mode. Prior to the work-function measurements, the samples were annealed at 100 °C for 30 min to remove adsorbed water2223.


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)

(a) Low- and (b) high-magnification cross-sectional scanning electron microscope images and (c) a schematic of a ZnO/Ag grating structure. (d) Schematic of the KPFM measurement setup in the glove box.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: (a) Low- and (b) high-magnification cross-sectional scanning electron microscope images and (c) a schematic of a ZnO/Ag grating structure. (d) Schematic of the KPFM measurement setup in the glove box.
Mentions: One-dimensional (1D) ZnO/Ag nanograting structures, with a period of 1 μm and a line-to-space ratio of 1:1, were prepared on polymer patterns, fabricated by imprint lithography, as shown in Fig. 1a–c. 100-nm-thick ZnO and 100-nm-thick Ag thin films were deposited on the nanopatterns at room temperature. For comparison, ZnO/Ag thin films were also prepared on flat Si wafers. Details of the sample fabrication procedures are available elsewhere14 and the Methods section. Because of the limited step coverage, the thickness of the both ZnO and Ag thin films at the sidewalls of the nanograting was only 38 nm, as shown in the scanning electron microscopy image (Fig. 1b) and the schematic of the nanograting (Fig. 1c). Figure 1d shows a schematic of our KPFM measurement system (XE-100, Park Systems) in a glove box filled with N2 gas. We used 5 mW green and red laser modules with wavelengths of 532 nm and 635 nm (LDC series, Korea), respectively, for the SPV measurements. The light was aligned to illuminate the sample area under the KPFM tip with an incident angle of 65°. At smaller angles, part of the laser light was blocked by the KPFM head. Depending on the incident angle, the energy of light-coupled SPP mode can be determined by the SPP dispersion relation (see Figure S1). The polarization of the laser light was adjusted with a linear polarizer to either transverse electric (TE) or transverse magnetic (TM) mode. Prior to the work-function measurements, the samples were annealed at 100 °C for 30 min to remove adsorbed water2223.

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.