Direct-Current Nanogenerator Driven by Ultrasonic Waves

Wang, Xudong; Song, Jinhui; Liu, Jin; Wang, Zhong Lin

doi:10.1126/science.1139366

Cited by 2,176 publications

(1,535 citation statements)

References 18 publications

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“…By using the unique electronic, optical, mechanical, and piezoelectric properties, ZnO NWs/NBs based field effect transistors, 2 ultraviolet (UV) lasers, 3 UV photo detectors, 4 light-emitting diodes, 5 solar cells, 6 piezoelectric transducer, and actuator 7 have been demonstrated. Most importantly, by utilizing semiconducting-piezoelectric coupled properties of ZnO, nanogenerators, 8,9 piezoelectric field effect transistors, 10 and piezoelectric diodes 11 and piezoelectric chemical sensors 12 were invented, which are the fundamental components of piezotronics. 13 Recently, research in the field of micro-and nanoelectromechanical system (MEMS and NEMS) is rapidly growing with considerable potential for ultra fast, high-sensitivity and low-power consumption devices.…”

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confidence: 99%

Flexible Piezotronic Strain Sensor

et al. 2008

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Strain sensors based on individual ZnO piezoelectric fine-wires (PFWs; nanowires, microwires) have been fabricated by a simple, reliable, and cost-effective technique. The electromechanical sensor device consists of a single electrically connected PFW that is placed on the outer surface of a flexible polystyrene (PS) substrate and bonded at its two ends. The entire device is fully packaged by a polydimethylsiloxane (PDMS) thin layer. The PFW has Schottky contacts at its two ends but with distinctly different barrier heights. The I-V characteristic is highly sensitive to strain mainly due to the change in Schottky barrier height (SBH), which scales linear with strain. The change in SBH is suggested owing to the strain induced band structure change and piezoelectric effect. The experimental data can be well-described by the thermionic emission-diffusion model. A gauge factor of as high as 1250 has been demonstrated, which is 25% higher than the best gauge factor demonstrated for carbon nanotubes. The strain sensor developed here has applications in strain and stress measurements in cell biology, biomedical sciences, MEMS devices, structure monitoring, and more.

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Flexible Piezotronic Strain Sensor

et al. 2008

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“…Recently, various novel devices have been fabricated using ZnO nanowires/nanobelts by utilizing its coupled piezoelectric and semiconducting properties (piezotronic effect), such as nanogenerators, 5,6 piezoelectric field effect transistors and chemical sensors, 7,8 piezoelectric diodes, 9 triggers, 10 transducer and actuator, 11 and flexible piezotronic strain sensors. 12 In this letter, we report a new type flexible piezotronic switch device that is built using a single ZnO piezoelectric fine wire (PFW) (nanowire, microwire).…”

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Piezoelectric-Potential-Controlled Polarity-Reversible Schottky Diodes and Switches of ZnO Wires

et al. 2008

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Using a two-end bonded ZnO piezoelectric-fine-wire (PFW) (nanowire, microwire) on a flexible polymer substrate, the strain-induced change in I-V transport characteristic from symmetric to diode-type has been observed. This phenomenon is attributed to the asymmetric change in Schottky-barrier heights at both source and drain electrodes as caused by the strain-induced piezoelectric potential-drop along the PFW, which have been quantified using the thermionic emission-diffusion theory. A new piezotronic switch device with an "on" and "off" ratio of ∼120 has been demonstrated. This work demonstrates a novel approach for fabricating diodes and switches that rely on a strain governed piezoelectric-semiconductor coupling process.Binary switching is the principle of many electronic devices for applications such as data storage and logic circuits. Up to now most of the nanoscale switches are operated by an electrostatic force between a suspended carbon nanotube (CNTs)/nanowire and its counter electrode to switch between "on" and "off" depending on mechanical contact. [1][2][3] As the size of the devices reaching nanoscale, a small gap of ∼10 nm is required to be maintained between the CNTs/nanowire and the electrode for electro-mechanical switching. In such a case, the van der Waals interaction between the CNT and the electrode may be strong enough to bind the two together so that the device cannot perform the "off" function as required. Furthermore, the random thermal vibration at the tip of CNT may also become sufficiently large at conventional operating temperatures, which can strongly increase the device instability. 4 As a result, the reliability, lifetime and manufacturability of these devices are challenged.The Schottky barrier diode, a metal-semiconductor (MS) rectifying junction that generally exhibits switching effect, may overcome the drawbacks. ZnO, a material that exhibits semiconductor and piezoelectric properties, is likely a candidate for fabricating diode-based switching devices.Recently, various novel devices have been fabricated using ZnO nanowires/nanobelts by utilizing its coupled piezoelectric and semiconducting properties (piezotronic effect), such as nanogenerators, 5,6 piezoelectric field effect transistors and chemical sensors, 7,8 piezoelectric diodes, 9 triggers, 10 transducer and actuator, 11 and flexible piezotronic strain sensors. 12 In this letter, we report a new type flexible piezotronic switch device that is built using a single ZnO piezoelectric fine wire (PFW) (nanowire, microwire). Its operation mechanism relies on the piezoelectric potential induced asymmetric change in Schottky-barrier height (SBH) at the source and drain electrodes. The change of SBH is caused by the combined effects from strain-induced band structure change and piezoelectric potential. The device demonstrated here presents a new electromechanical switch built based on piezotronic effect. 13 For this study, the device was fabricated by bonding an ultralong ZnO PFW laterally on a polystyrene (PS) substrate,...

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“…7,8 Growth of aligned ZnO NWs has been achieved on GaN via physical vapor deposition (PVD) at a high temperature of 500-800°C, with the use of gold as a catalyst, 9 in which the catalyst initiated and guided the growth, and the epitaxial orientation relationship between the ZnO NWs and the GaN substrate led to the aligned growth. This strategy may have the risk of introducing catalyst residual atoms into the ZnO NWs, which is incompatible with silicon technology.…”

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confidence: 99%