Piezo-phototronic Effect Enhanced Visible and Ultraviolet Photodetection Using a ZnO-CdS Core-Shell Micro/nanowire

School of Material Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
ACS Nano (Impact Factor: 12.88). 09/2012; 6(10):9229-36. DOI: 10.1021/nn3035765
Source: PubMed


The piezo-phototronic effect is about the use of the piezoelectric potential created inside some materials for enhancing the charge carrier generation or separation at the metal-semiconductor contact or pn junction. In this paper, we demonstrate the impact of the piezo-phototronic effect on the photon sensitivity for a ZnO-CdS core-shell micro/nanowire based visible and UV sensor. CdS nanowire arrays were grown on the surface of a ZnO micro/nanowire to form a ZnO-CdS core-shell nanostructure by a facile hydrothermal method. With the two ends of a ZnO-CdS wire bonded on a polymer substrate, a flexible photodetector was fabricated, which is sensitive simultaneously to both green light (548 nm) and UV light (372 nm). Furthermore, the performance of the photon sensor is much enhanced by the strain-induced piezopotential in the ZnO core through modulation of the Schottky barrier heights at the source and drain contacts. This work demonstrates a new application of the piezotronic effect in photon detectors.

21 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigate the electronic band structures of Ge/Si core–shell nanowires (CSNWs) and devise a way to realize the electron quantum well at Ge core atoms with first-principles calculations. We reveal that the electronic band engineering by the quantum confinement and the lattice strain can induce the type-I/II band alignment transition, and the resulting type-I band alignment generates the electron quantum well in Ge/Si CSNWs. We also find that the type-I/II transition in Ge/Si CSNWs is highly related to the direct to indirect band gap transition through the analysis of charge density and band structures. In terms of the quantum confinement, for [100] and [111] directional Ge/Si CSNWs, the type-I/II transition can be obtained by decreasing the diameters, whereas a [110] directional CSNW preserves the type-II band alignment even at diameters as small as 1 nm. By applying a compressive strain on [110] CSNWs, the type-I band alignment can be formed. Our results suggest that Ge/Si CSNWs can have the type-I band alignment characteristics by the band structure engineering, which enables both n-type and p-type quantum-well transistors to be fabricated using Ge/Si CSNWs for high-speed logic applications.
    Journal of Physical Chemistry Letters 01/2013; 4(1-1):121-126. DOI:10.1021/jz301975v · 7.46 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A low-cost and efficient photocatalytic reactor for environmental treatment and green technology was presented. ZnO nanorods firmly growing on polycarbonate optical disk substrate are generally perpendicular to the substrate as the immobilized photocatalyst of the spinning disk reactor. The photocatalytic efficiency and durability of the ZnO nanorods are effectively demonstrated.
    Optics Express 03/2013; 21(6):7240-9. DOI:10.1364/OE.21.007240 · 3.49 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Branched ZnO-CdS double-shell NW array on the surface of a carbon fiber (CF/ZnO-CdS) was successfully synthesized via a facile two-step hydrothermal method. Based on a single CF/ZnO-CdS wire on a polymer substrate, a flexible photodetector was fabricated, which exhibited ultrahigh photon responsivity under illuminations of blue light (1.11×105 A/W, 8.99×10-8 W/cm2, 480 nm), green light (3.83×104 A/W, 4.48×10-8 W/cm2, 548 nm) and UV light (1.94×105 A/W, 1.59×10-8 W/cm2, 372 nm) respectively. The responsivity of this broadband photon sensor was enhanced further by as high as 60% when the device was subjected to a -0.38% compressive strain. This is because that the strain induced a piezopotential in ZnO which tunes the barrier height at the ZnO-CdS heterojunction interface, leading to an optimized optoelectronic performance. This work demonstrates a promising application of piezo-phototronic effect in nano-heterojunction array based photon detectors.
    ACS Nano 04/2013; 7(5). DOI:10.1021/nn401232k · 12.88 Impact Factor
Show more


21 Reads