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ABSTRACT: The glancing-angle deposition technique can be used to control the growth direction of InN nanorods and nanowires, enabling potential applications for fabricating nanopiezotronics and nanogenerators. This study demonstrates the feasibility of using an obliquely aligned InN nanorod array to harvest electricity from the ambient environment, leading to the realization of self-powered nanodevices.
Advanced Materials 11/2012; · 13.88 Impact Factor
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ABSTRACT: This paper proposes an obliquely aligned InN nanorod array to maximize nanorod deformation in the application of nanopiezotronics. The surface-dependent piezotronic I-V characteristics of the InN nanorod array with exposed polar (0002) and semipolar ( ̅1102) planes were studied by conductive atomic force microscopy. The effects of the piezopotential, created in the InN under straining, and the surface quantum states on the transport behavior of charge carriers in different crystal planes of the InN nanorod were investigated. The crystal plane-dependent electron density in the electron surface accumulation layer and the strain-dependent piezopotential distribution modulate the interfacial contact of the Schottky characteristics for the (0002) plane and the quasi-ohmic behavior for the ( ̅1102) plane. Regarding the piezotronic properties under applied forces, the Schottky barrier height increases in conjunction with the deflection force with high current density at large biases because of tunneling. The strain-induced piezopotential can thus tune the transport process of the charge carriers inside the InN nanorod over a larger range than in ZnO. The quantized surface electron accumulation layer is demonstrated to modulate the piezopotential-dependent carrier transport at the metal/InN interfaces and become an important factor in the design of InN-based piezotronic devices and nanogenerators.
Nano Letters 12/2011; 12(2):562-8. · 13.20 Impact Factor
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ABSTRACT: Gallium implantation of ZnO by a focused-ion beam is used to create a mask for ZnO dry etching with hydrogen. Effects of Ga(+) fluence on the etch stop properties and the associated mechanisms are investigated. The fluence of 2.8 × 10(16) cm(-2) is determined to be optimum to render the best mask quality. While lower fluences would cause less etching selectivity, higher fluences would cause erosion of the surface and particles to be precipitated on the surface after H(2) treatment at high temperature. In contrast to the commonly adopted gallium oxide formation on Si, transmission electron microscopy analysis reveals that, for the fluences ≤ 2.8 × 10(16) cm(-2), Ga(+) ions are incorporated as dopants into ZnO without any second phases or precipitates, indicating the Ga-doped ZnO layer behaves as a mask for H(2) etching due to the higher electronegativity of Ga(+) towards oxygen. However, for the fluences ≥ 4.6 × 10(16) cm(-2), the surface particles are responsible for the etch stop and are identified as ZnGa(2)O(4). We finally demonstrate a complicated pattern of 'NCKU' on ZnO by using this technique. The study not only helps clarify the related mechanisms, but also suggests a feasible extension of the etch stop process that can be applied to more functional material.
Nanotechnology 12/2010; 21(50):505703. · 3.98 Impact Factor
