Limits...
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

Two types of devices fabricated for comparison. (a) Electric model, schematic and SEM of the fabricated Schottky diode, I-V showing good rectifying behavior; and (b) Electric model, schematic and SEM of the device with ohmic contact on both sides, I-V show clear ohmic behavior.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211437&req=5

Figure 3: Two types of devices fabricated for comparison. (a) Electric model, schematic and SEM of the fabricated Schottky diode, I-V showing good rectifying behavior; and (b) Electric model, schematic and SEM of the device with ohmic contact on both sides, I-V show clear ohmic behavior.

Mentions: NWs were then ultrasonically dispersed in ethanol and were placed onto a gold patterned insulated SiO2 substrate. After drying out the suspension, gold was re-evaporated onto one side of some selected ZnO NWs by lithography and lift-off process in order to form a stable Schottky contact. Focused ion beam (FIB) is used to deposit Ga induced Pt on the contact between the NW and the gold electrodes for eliminating the Schottky barriers and form high quality ohmic contacts [12]. Some samples were prepared by making ohmic contacts to both the sides. The scanning electron microscopic (SEM) images and the schematics of the device are shown in the Figure 3.


Single nanowire-based UV photodetectors for fast switching.

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

Two types of devices fabricated for comparison. (a) Electric model, schematic and SEM of the fabricated Schottky diode, I-V showing good rectifying behavior; and (b) Electric model, schematic and SEM of the device with ohmic contact on both sides, I-V show clear ohmic behavior.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Two types of devices fabricated for comparison. (a) Electric model, schematic and SEM of the fabricated Schottky diode, I-V showing good rectifying behavior; and (b) Electric model, schematic and SEM of the device with ohmic contact on both sides, I-V show clear ohmic behavior.
Mentions: NWs were then ultrasonically dispersed in ethanol and were placed onto a gold patterned insulated SiO2 substrate. After drying out the suspension, gold was re-evaporated onto one side of some selected ZnO NWs by lithography and lift-off process in order to form a stable Schottky contact. Focused ion beam (FIB) is used to deposit Ga induced Pt on the contact between the NW and the gold electrodes for eliminating the Schottky barriers and form high quality ohmic contacts [12]. Some samples were prepared by making ohmic contacts to both the sides. The scanning electron microscopic (SEM) images and the schematics of the device are shown in the Figure 3.

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