Toward a Systematic Understanding of Photodetectors Based on Individual Metal Oxide Nanowires

The Journal of Physical Chemistry C (Impact Factor: 4.77). 09/2008; 112:14639-14644. DOI: 10.1021/jp804614q


We present a set of criteria to optimize photodetectors based on n-type metal oxide nanowires and a comparison methodology capable of overcoming the present lack of systematic studies dealing with such devices. The response of photoconductors is enhanced following different fabrication strategies, such as diminishing the distance between the electrical contacts, increasing the width of the photoactive area, or improving the electrical mobility of the nanomaterials. The validity of the theoretical background is verified by experimental results obtained with devices based on ZnO nanowires. The performances of our devices show that the normalized gain of single ZnO nanowire-based photodetectors exceeds those of thin films.

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    • "Nanostructured metal oxide semiconductors (NMOSs) have attracted much attention because of their unique size and dimensionality-dependent physical and chemical properties as well as promising application as key components in nanoscale devices123. Compared with micro or bulk counterparts, NMOSs exhibit novel structural characteristics and size confinement effects as well as unique properties[4]. Cupric oxide (CuO) nanostructures with large surface-tovolume ratio are of particular interest among NMOSs, because of their interesting properties as a p-type semiconductor with a narrow band gap (1.4 eV) and promising applications in batteries, supercapacitors, solar cell, gas sensor and photodetectors5678. of the template is preferable due to fact that this rigid substrate usually serves as an electrode as well as to establish contacts to both ends of the pores (or of the nanorods) while the AAO is still attached to the substrate[20]. "
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    • "These differences can be fully explained by taking into account the strong influence of surface-mediated electron–hole separation effects in nano-size materials [26]: charge separation slows down the electron–hole recombination times Fig. 4. (a) Photocurrent generated at different light intensities (˚ ph ) and bias voltages (V bias ). (b) Summary of the photocurrent response as a function of photon flux (˚ ph ), where the slope is a direct measurement of g ph , after geometry (W,L) and bias voltage (V bias ) correction [45]. (and thus the response times), leading to larger photocurrent values. "
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    ABSTRACT: The integration of one dimensional (1D) nanostructures of non-industry-standard semiconductors in functional devices following bottom-up approaches is still an open challenge that hampers the exploitation of all their potential. Here, we present a simple approach to integrate metal oxide nanowires in electronic devices based on controlled dielectrophoretic positioning together with proof of concept devices that corroborate their functionality. The method is flexible enough to manipulate nanowires of different sizes and compositions exclusively using macroscopic solution-based techniques in conventional electrode designs. Our results show that fully functional devices, which display all the advantages of single-nanowire gas sensors, photodetectors, and even field-effect transistors, are thus obtained right after a direct assembly step without subsequent metallization processing. This paves the way to low cost, high throughput manufacturing of general-purpose electronic devices based on non-conventional and high quality 1D nanostructures driving up many options for high performance and new low energy consumption devices.
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    • "The normalized photoconductive gain is thus independent of the device geometry and the experimental conditions. Our fabricated device has a gain of 10 6 , which is lower than that reported by (Soci et al. 2007) (gain of the order of 10 8 ) and (Chen et al. 2013) (gain of the order of 10 7 ), but higher than that reported by (Prades et al. 2008) (gain of the order of 10 4 ). However, when the experimental conditions are taken into account, our results of normalized gain is at least an order of magnitude higher than those reported earlier. "
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