Controlled Growth of ZnO Nanowires and Their Optical Properties

Yang, Peidong; Yan, Haoquan; Mao, Samuel S.; Russo, Richard E.; Johnson, Justin C.; Saykally, Richard J.; Morris, N.; Pham, Johnny D.; He, Rongrui; Choi, Hyunsik

doi:10.1002/1616-3028(20020517)12:5<323::aid-adfm323>3.0.co;2-g

Cited by 1,769 publications

(1,105 citation statements)

References 19 publications

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“…One-dimensional (1D) nanostructures, such as nanotubes, nanowires and nanobelts, have attracted extraordinary attention for their potential applications in device and interconnect integration in nanoelectronics and molecular electronics [1 -5]. Although different levels of growth controls for nanowires (including positional, orientational, diameter, and density control) have been achieved [6], the shape control of nanostructures is not easily obtained. The synthesis of complex structures of rod-based CdSe nanocrystals e.g.…”

supporting

confidence: 41%

The octa-twin tetraleg ZnO nanostructures

Dai

Zhang

Wang

2003

Solid State Communications

171

113

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We have developed a simple solid-vapor approach for controlled growth of the tetraleg ZnO nanostructure at high yield. The length of the tetraleg is 2 -3 mm and the edge size of its centering nucleus is 70 -200 nm. Our electron microscopy study gives the first direct evidence about the existence of the octahedral multiple twin nucleus, which is confirmed to be responsible for the formation of the tetraleg ZnO nanostructure. The tetraleg ZnO nanostructure is likely to be a candidate as building blocks for contructing photonic crystals. Nanoscale materials exhibit a wide range of electrical and optical properties that depend sensitively on both shape and size, and are of both fundamental and technological interest. One-dimensional (1D) nanostructures, such as nanotubes, nanowires and nanobelts, have attracted extraordinary attention for their potential applications in device and interconnect integration in nanoelectronics and molecular electronics [1 -5]. Although different levels of growth controls for nanowires (including positional, orientational, diameter, and density control) have been achieved [6], the shape control of nanostructures is not easily obtained. The synthesis of complex structures of rod-based CdSe nanocrystals e.g. arrow and teardrop, has demonstrated some success in this direction [7 -9]. Since the novel properties of nanomaterials depend sensitively on their shape and size, the development of synthetic methods and an understanding of the mechanism by which the shape and size of nanostructures can be easily controlled is a key issue in nanoscience.ZnO exhibits a direct bandgap of 3.37 eV at room temperature with a large exciton binding energy of 60 meV. The strong exciton binding energy, which is much larger than that of GaN (25 meV) and the thermal energy at room temperature (26 meV), can ensure an efficient exciton emission at room temperature under low excitation energy [10 -11]. As a consequence, ZnO is recognized as a promising photonic material in the blue-UV region. Room temperature UV lasing properties have recently been demonstrated from ZnO epitaxial films, microcrystalline thin films, and nanoclusters [12][13][14][15]. The synthesis of 1D single-crystalline ZnO nanostructures has been of growing interest owing to their promising application in nanoscale optoelectronic devices. Single-crystalline ZnO nanowires have been synthesized successfully in several groups [16][17][18][19][20]. Wang et al. reported the synthesis of oxide nanobelts by simply evaporating the commercial metal oxide powders at high temperatures [3,[19][20]. The assynthesized oxide nanobelts are pure, structurally uniform, and single crystalline, and most of them are of free from 0038-1098/03/$ -see front matter q

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supporting

confidence: 41%

The octa-twin tetraleg ZnO nanostructures

Dai

Zhang

Wang

2003

Solid State Communications

171

113

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“…Thus, the resulting epitaxially grown ZnO NWs prefer to have a hexagonal cross section. 1 The free NWs are typically grown by sublimation of ZnO powder without introducing a catalyst. 3 An interesting phenomenon in the free NW is experimentally-observed planar defects parallel to the (0001) polar surfaces.…”

Section: Structure and Simulation Detailsmentioning

confidence: 99%

“…1,2,3,4,5,6 . ZnO NWs have been found, primarily due to surface effects resulting from their large surface to volume ratio, to have substantially different properties from their bulk counterparts.…”

Section: Introductionmentioning

confidence: 99%

Polar surface effects on the thermal conductivity of ZnO nanowires: a shell-like surface reconstruction-induced preserving mechanism

2013

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We perform molecular dynamics (MD) simulations to investigate the effect of polar surfaces on the thermal transport in zinc oxide (ZnO) nanowires. We find that the thermal conductivity in nanowires with free polar (0001) surfaces is much higher than in nanowires that have been stabilized with reduced charges on the polar (0001) surfaces, and also hexagonal nanowires without any transverse polar surfaces, where the reduced charge model has been proposed as a promising stabilization mechanism for the (0001) polar surfaces for ZnO nanowires. From normal mode analysis, we show that the higher thermal conductivity is due to a shell-like reconstruction that occurs for the free polar surfaces. This shell-like reconstruction suppresses twisting motion in the nanowires such that the bending phonon modes are not scattered by the other phonon modes, and leads to substantially higher thermal conductivity in the ZnO nanowire with free polar surfaces. Furthermore, the autocorrelation function of the normal mode coordinate is utilized to extract the phonon lifetime, which leads to a concise explanation for the higher thermal conductivity in ZnO nanowires with free polar surfaces. Our work demonstrates that ZnO nanowires without polar surfaces, which exhibit low thermal conductivity, are more promising candidates for thermoelectric applications than nanowires with polar surfaces (and also high thermal conductivity).

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“…Numerous techniques have recently been developed to synthesize quasi-1D ZnO nanostructures, (Baranov et al 2004;Liu et al, 2004;Xia et al, 2003;Yang et al, 2002;Yao et al, 2002;Yin et al, 2004;Wang et al, 2004; including growth with or without catalysts by a vapour-liquid-solid epitaxial (VLS) mechanism (Yang et al, 2002;Yao et al, 2002;Wang et al, 2004), microwave plasma growth and solution methods Yin et al, 2004). An important issue in the fabrication of nanostructures is the control of the shape and size of nanomaterials, both of which affect their optical and electrical properties.…”

Section: Zno Nanorodsmentioning

confidence: 44%

Multicolor Luminescence from Semiconductor Nanocrystal Composites Tunable in an Electric Field

Panin¹

2012

Cathodoluminescence

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Controlled Growth of ZnO Nanowires and Their Optical Properties

Cited by 1,769 publications

References 19 publications

The octa-twin tetraleg ZnO nanostructures

The octa-twin tetraleg ZnO nanostructures

Polar surface effects on the thermal conductivity of ZnO nanowires: a shell-like surface reconstruction-induced preserving mechanism

Multicolor Luminescence from Semiconductor Nanocrystal Composites Tunable in an Electric Field

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