Flexible Piezotronic Strain Sensor

Zhou, Jun; Gu, Yudong; Peng, Fei; Mai, Wenjie; Gao, Yixin; Yang, Rusen; Bao, Gang; Wang, Zhong Lin

doi:10.1021/nl802367t

Cited by 763 publications

(746 citation statements)

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“…The strain in the microwire was quantified by the distance at which the substrate was deflected. 12 In Figure 2b, by increasing the strain step-by-step, the diode-like IϪV characteristic finally changed into a totally off status across the entire voltage range. It worked like a piezoelectric switch, showing a huge transformation in the electrical transport characteristic by the piezoelectric effect.…”

Section: Resultsmentioning

confidence: 98%

Designing the Electric Transport Characteristics of ZnO Micro/Nanowire Devices by Coupling Piezoelectric and Photoexcitation Effects

et al. 2010

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S emiconductor nanowires are the fundamental materials for fabricating a wide range of nanodevices. 1Ϫ5 In the oxide family, ZnO nanowires and nanobelts have been widely studied as a key 1D oxide nanomaterial for numerous applications. Due to the unique piezoelectric and semiconducting coupled properties, a range of novel nanodevices of ZnO have been developed, such as nanogenerators, 6Ϫ9 piezoelectric field effect transistors, 10 piezoelectric diode, 11 and strain sensors. 12 A direct band gap of 3.4 eV and a large exciton binding energy (60 meV) at room temperature make ZnO a prominent candidate in optical applications, such as an ultraviolet detector, 13Ϫ16 optical pumped laser, 17,18 and light emitting diodes. 19 Recently, the photoconducting response at different degrees of straining of a ZnO nanowire has been studied using in situ transmission electron microscopy. 20 Although a lot of progress has been made in each research field as stated above, very limited research has been conducted on the localized and quantitatively controlled coupling of the piezoelectric effect and photoexcitation on a ZnO nanowire nanodevice.In this paper, by introducing a controllable stepping strain and using a focused laser beam, we have investigated the localized coupling between the piezoelectric effect and photoexcitation of ZnO microwire devices that exhibit various controlled electrical transport characteristics. By using microwire devices with SchottkyϪOhmic, OhmicϪOhmic, and SchottkyϪSchottky contacts, we have demonstrated the finetuning of contact characteristics, such as from Schottky to Ohmic or from Ohmic to Schottky, by varying the individual contributions made by piezoelectricity and photoexcitation at local contacts. On the basis of this concept, a design of electric transport properties is demonstrated. This study reveals a new principle for controlling the coupling among mechanical, electrical, and optical properties, which can be the basis for fabricating piezo-photonic-electronic nanodevices, which is referred to as piezophototronics. RESULTS AND DISCUSSIONOur device was fabricated using a single micro/nanowire of ZnO (see the Experimental Methods for details). First, we investigated the photoresponse of a microwire device with photoexcitation at different locations along the ZnO microwire. Figure 1a is a superimposed optical image taken from a ZnO microwire device with the laser spot focused at different positions, as schematically shown on the right-hand side. Points P1, P2, and P3, respectively, represent the positions at the left-hand metalϪZnO contact, central channel region, and right-hand metalϪZnO contact.

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Section: Resultsmentioning

confidence: 98%

Designing the Electric Transport Characteristics of ZnO Micro/Nanowire Devices by Coupling Piezoelectric and Photoexcitation Effects

et al. 2010

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“…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.…”

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confidence: 99%

“…The detail device fabrication process was introduced elsewhere. 12 Briefly, single ZnO PFW (typical diameter of several micrometers and length of several hundred micrometers to several millimeters), which was synthesized by a high temperature physical vapor deposition process, 14 was placed on PS substrate (typical length of ∼3 cm, width of ∼5 mm and thickness of 1 mm) by using a probe station under optical microscopy. Then silver paste was applied at both ends of the ZnO PFW to fix its two ends tightly on the substrate; silver paste was also used as the source and drain electrodes.…”

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confidence: 99%

“…Previously, we focused on the devices which originally exhibit rectifying I-V behavior, and flexible piezotronic strain sensors based on those devices have been demonstrated. 12 In this study, we focus only on the devices that have symmetric or nearly symmetric I-V behavior. Typical I-V characteristics under various compressive strains (Device no.…”

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confidence: 99%

“…By assuming S, A ** , T, and N D are to be known, φ s can, in principle, be derived from the ln I-V plot. 12 Subsequently, the strain-induced change in SBH can be determine by 12,17,18 …”

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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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Piezotronics and Piezo‐Phototronics

Wang

2012

Wiley Encyclopedia of Electrical and Electronics Engineering

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Most of the current electronics are operated by an externally applied voltage, which tunes the charge transport inside the device. Here, we introduce a new concept that uses the generated potential in a crystal to control the charge transport in the device, which is a new principle for fabricating new electronics that are controlled by externally applied strain/stress. As a result of the polarization of ions in a crystal that has noncentral symmetry in materials such as the wurtzite‐structured ZnO, GaN, and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a stress. Because of the simultaneous possession of piezoelectricity and semiconductor properties, the piezopotential created in the crystal has a strong effect on the carrier transport at the interface/junction. Piezotronics is about the devices fabricated using the piezopotential as a “gate” voltage to tube/control charge carrier transport at a contact or junction. The piezo‐phototronic effect is about using the piezopotential to control the carrier generation, transport, separation, and/or recombination to improve the performance of optoelectronic devices, such as the photon detector, solar cell, and light‐emitting diode (LED) devices. The objective of this review article is to introduce the fundamentals of piezotronics and piezo‐phototronics. A perspective is given about their potential applications in sensors, human–silicon technology interfacing, microelectromechanical systems (MEMS), nanorobotics, and energy sciences.

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Flexible Piezotronic Strain Sensor

Cited by 763 publications

References 31 publications

Designing the Electric Transport Characteristics of ZnO Micro/Nanowire Devices by Coupling Piezoelectric and Photoexcitation Effects

Designing the Electric Transport Characteristics of ZnO Micro/Nanowire Devices by Coupling Piezoelectric and Photoexcitation Effects

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

Piezotronics and Piezo‐Phototronics

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