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Single nanowire-based UV photodetectors for fast switching.

Ul Hasan K, Alvi NH, Lu J, Nur O, Willander M - Nanoscale Res Lett (2011)

Bottom Line: Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs.The photodetector shows high stability, reversibility, and sensitivity to UV light.The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Science and Technology (ITN) Linköping University, Campus Norrköping, SE-601 74 Norrköping, Sweden. kamran.ul.hasan@liu.se.

ABSTRACT
Relatively long (30 µm) high quality ZnO nanowires (NWs) were grown by the vapor-liquid-solid (VLS) technique. Schottky diodes of single NW were fabricated by putting single ZnO NW across Au and Pt electrodes. A device with ohmic contacts at both the sides was also fabricated for comparison. The current-voltage (I-V) measurements for the Schottky diode show clear rectifying behavior and no reverse breakdown was seen down to -5 V. High current was observed in the forward bias and the device was found to be stable up to 12 V applied bias. The Schottky barrier device shows more sensitivity, lower dark current, and much faster switching under pulsed UV illumination. Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs. The NW was treated with oxygen plasma to improve the switching. The photodetector shows high stability, reversibility, and sensitivity to UV light. The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors.

No MeSH data available.


Related in: MedlinePlus

Structural characterization of the ZnO nanowires. (a) HRTEM image of the edge of an as-synthesized ZnO nanowire. The spacing of 0.26 nm between adjacent lattice planes corresponds to (002) lattice planes of ZnO and <0001> growth direction is also shown; (b) XRD spectrum of the ZnO nanowires.
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Figure 2: Structural characterization of the ZnO nanowires. (a) HRTEM image of the edge of an as-synthesized ZnO nanowire. The spacing of 0.26 nm between adjacent lattice planes corresponds to (002) lattice planes of ZnO and <0001> growth direction is also shown; (b) XRD spectrum of the ZnO nanowires.

Mentions: The samples were annealed at 600°C in ambient argon to improve the crystal quality and minimize the defects. High-resolution transmission electron microscopy (HRTEM) image (Figure 2a) indicates the good monocrystalline quality structure of the ZnO NW. Lattice spacing is approximately 0.26 nm between the two adjacent (002) lattice planes and it confirms the <0001> growth direction [10]. Furthermore, the X-ray diffraction (XRD) pattern of the ZnO nanowires is shown in Figure 2b. The strong (002) peak and weak (004) peak reconfirm that the ZnO nanowires preferentially grow along the c-axis <0001> direction. Higher intensity and narrow spectral width of the (002) peak affirms that the grown ZnO has high-purity wurtzite hexagonal phase [11].


Single nanowire-based UV photodetectors for fast switching.

Ul Hasan K, Alvi NH, Lu J, Nur O, Willander M - Nanoscale Res Lett (2011)

Structural characterization of the ZnO nanowires. (a) HRTEM image of the edge of an as-synthesized ZnO nanowire. The spacing of 0.26 nm between adjacent lattice planes corresponds to (002) lattice planes of ZnO and <0001> growth direction is also shown; (b) XRD spectrum of the ZnO nanowires.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211437&req=5

Figure 2: Structural characterization of the ZnO nanowires. (a) HRTEM image of the edge of an as-synthesized ZnO nanowire. The spacing of 0.26 nm between adjacent lattice planes corresponds to (002) lattice planes of ZnO and <0001> growth direction is also shown; (b) XRD spectrum of the ZnO nanowires.
Mentions: The samples were annealed at 600°C in ambient argon to improve the crystal quality and minimize the defects. High-resolution transmission electron microscopy (HRTEM) image (Figure 2a) indicates the good monocrystalline quality structure of the ZnO NW. Lattice spacing is approximately 0.26 nm between the two adjacent (002) lattice planes and it confirms the <0001> growth direction [10]. Furthermore, the X-ray diffraction (XRD) pattern of the ZnO nanowires is shown in Figure 2b. The strong (002) peak and weak (004) peak reconfirm that the ZnO nanowires preferentially grow along the c-axis <0001> direction. Higher intensity and narrow spectral width of the (002) peak affirms that the grown ZnO has high-purity wurtzite hexagonal phase [11].

Bottom Line: Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs.The photodetector shows high stability, reversibility, and sensitivity to UV light.The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Science and Technology (ITN) Linköping University, Campus Norrköping, SE-601 74 Norrköping, Sweden. kamran.ul.hasan@liu.se.

ABSTRACT
Relatively long (30 µm) high quality ZnO nanowires (NWs) were grown by the vapor-liquid-solid (VLS) technique. Schottky diodes of single NW were fabricated by putting single ZnO NW across Au and Pt electrodes. A device with ohmic contacts at both the sides was also fabricated for comparison. The current-voltage (I-V) measurements for the Schottky diode show clear rectifying behavior and no reverse breakdown was seen down to -5 V. High current was observed in the forward bias and the device was found to be stable up to 12 V applied bias. The Schottky barrier device shows more sensitivity, lower dark current, and much faster switching under pulsed UV illumination. Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs. The NW was treated with oxygen plasma to improve the switching. The photodetector shows high stability, reversibility, and sensitivity to UV light. The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors.

No MeSH data available.


Related in: MedlinePlus