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.
Highlights
Zinc oxide (ZnO) is a unique material with semiconducting and piezoelectric dual properties
The I-V characteristics of our ZnO NW Schottky diode shown in Figure 3a demonstrate a good rectifying behavior
When the UV illumination is switched on or off, the oxygen is desorbed or readsorbed in the interfacial region in the premises of the metal contact in Schottky diodes and it reduces the Schottky barrier height, whereas for the device with ohmic contacts on the both sides, it happens throughout the NW surface
Summary
Zinc oxide (ZnO) is a unique material with semiconducting and piezoelectric dual properties. A Schottky barrier diode exhibits faster switching and lower turn-on voltages as compared to a p-n junction diode and there is some optical loss in the p-region of a p-n diode That makes it a very useful for electronic and optoelectronic application. 30 μm) were used in this study that show very fast response on full length device (due to the reduced dimensionality of the active area at the Schottky ul Hasan et al Nanoscale Research Letters 2011, 6:348 http://www.nanoscalereslett.com/content/6/1/348 junction) and potentially allows fabrication of several diodes on a single NW. For the growth of ZnO nanowires, a thin film of pure Au (99.9%) was used as a catalyst and was deposited on the Si substrate in a high vacuum metallization chamber. The scanning electron microscopic (SEM) images and the schematics of the device are shown in the Figure 3
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