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Piezoelectric effect in chemical vapour deposition-grown atomic-monolayer triangular molybdenum disulfide piezotronics.

Qi J, Lan YW, Stieg AZ, Chen JH, Zhong YL, Li LJ, Chen CD, Zhang Y, Wang KL - Nat Commun (2015)

Bottom Line: Here we report the experimental study of the theoretically predicted piezoelectric effect in triangle monolayer MoS2 devices under isotropic mechanical deformation.The underlying mechanism of strain-induced in-plane charge polarization is proposed and discussed using energy band diagrams.Our results provide evidence for strain-gating monolayer MoS2 piezotronics, a promising avenue for achieving augmented functionalities in next-generation electronic and mechanical-electronic nanodevices.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road 30, Beijing 100083, China.

ABSTRACT
High-performance piezoelectricity in monolayer semiconducting transition metal dichalcogenides is highly desirable for the development of nanosensors, piezotronics and photo-piezotransistors. Here we report the experimental study of the theoretically predicted piezoelectric effect in triangle monolayer MoS2 devices under isotropic mechanical deformation. The experimental observation indicates that the conductivity of MoS2 devices can be actively modulated by the piezoelectric charge polarization-induced built-in electric field under strain variation. These polarization charges alter the Schottky barrier height on both contacts, resulting in a barrier height increase with increasing compressive strain and decrease with increasing tensile strain. The underlying mechanism of strain-induced in-plane charge polarization is proposed and discussed using energy band diagrams. In addition, a new type of MoS2 strain/force sensor built using a monolayer MoS2 triangle is also demonstrated. Our results provide evidence for strain-gating monolayer MoS2 piezotronics, a promising avenue for achieving augmented functionalities in next-generation electronic and mechanical-electronic nanodevices.

No MeSH data available.


Related in: MedlinePlus

Deformation of the MoS2 monolayer and electromechanical properties of the device.(a) Deformation of the MoS2 monolayer under different forces applied by the AFM tip. Optical image of the measured MoS2 device (inset) denoting the tested 2.5 × 2.5-μm2 area by a black dashed rectangle. (b) I–Vb curves of the measured MoS2 device under a force applied in the centre of the tested region cycled from 0 to 12.5 nN and back to 0 nN, where the inset reveals the measured current under variable mechanical load at a fixed bias voltage of 0.55 V.
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f2: Deformation of the MoS2 monolayer and electromechanical properties of the device.(a) Deformation of the MoS2 monolayer under different forces applied by the AFM tip. Optical image of the measured MoS2 device (inset) denoting the tested 2.5 × 2.5-μm2 area by a black dashed rectangle. (b) I–Vb curves of the measured MoS2 device under a force applied in the centre of the tested region cycled from 0 to 12.5 nN and back to 0 nN, where the inset reveals the measured current under variable mechanical load at a fixed bias voltage of 0.55 V.

Mentions: To identify the maximum deformation, which could be achieved in these MoS2 devices, the relationship between the applied force and deformation was measured through AFM-based force spectroscopy using the PeakForce Quantitative Nanomechanical Property Mapping mode. Deformation maps over a 2.5 × 2.5 μm2 area in the central region of MoS2 device shown in the inset of Fig. 2a were acquired under variable mechanical loading forces applied by AFM tip, as seen in Supplementary Fig. 3. Figure 2a provides the load-dependent deformation of the monolayer MoS2 device. Owing to physical constraints imposed by the underlying substrate, mechanical deformation of the MoS2 monolayer saturated when the applied force exceeded an average of 25 nN for all of measured devices. The current–voltage (I–Vb) characteristics of these devices were investigated under variable mechanical loads using the circuit defined by a S and D as seen in the inset of Fig. 2a. By cycling the applied loading force from 0 to 12.5 nN and back to 0 nN with the AFM tip in contact with the centre of the denoted area, measured I–Vb curves shown in Fig. 2b reveal a decrease in current with increasing force and this decrease can be reversed when the strain was released. It can also be clearly seen that the measured current through the device at a fixed voltage (0.55 V) monotonically decreased as deformation increased, as shown in the inset of Fig. 2b.


Piezoelectric effect in chemical vapour deposition-grown atomic-monolayer triangular molybdenum disulfide piezotronics.

Qi J, Lan YW, Stieg AZ, Chen JH, Zhong YL, Li LJ, Chen CD, Zhang Y, Wang KL - Nat Commun (2015)

Deformation of the MoS2 monolayer and electromechanical properties of the device.(a) Deformation of the MoS2 monolayer under different forces applied by the AFM tip. Optical image of the measured MoS2 device (inset) denoting the tested 2.5 × 2.5-μm2 area by a black dashed rectangle. (b) I–Vb curves of the measured MoS2 device under a force applied in the centre of the tested region cycled from 0 to 12.5 nN and back to 0 nN, where the inset reveals the measured current under variable mechanical load at a fixed bias voltage of 0.55 V.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4491182&req=5

f2: Deformation of the MoS2 monolayer and electromechanical properties of the device.(a) Deformation of the MoS2 monolayer under different forces applied by the AFM tip. Optical image of the measured MoS2 device (inset) denoting the tested 2.5 × 2.5-μm2 area by a black dashed rectangle. (b) I–Vb curves of the measured MoS2 device under a force applied in the centre of the tested region cycled from 0 to 12.5 nN and back to 0 nN, where the inset reveals the measured current under variable mechanical load at a fixed bias voltage of 0.55 V.
Mentions: To identify the maximum deformation, which could be achieved in these MoS2 devices, the relationship between the applied force and deformation was measured through AFM-based force spectroscopy using the PeakForce Quantitative Nanomechanical Property Mapping mode. Deformation maps over a 2.5 × 2.5 μm2 area in the central region of MoS2 device shown in the inset of Fig. 2a were acquired under variable mechanical loading forces applied by AFM tip, as seen in Supplementary Fig. 3. Figure 2a provides the load-dependent deformation of the monolayer MoS2 device. Owing to physical constraints imposed by the underlying substrate, mechanical deformation of the MoS2 monolayer saturated when the applied force exceeded an average of 25 nN for all of measured devices. The current–voltage (I–Vb) characteristics of these devices were investigated under variable mechanical loads using the circuit defined by a S and D as seen in the inset of Fig. 2a. By cycling the applied loading force from 0 to 12.5 nN and back to 0 nN with the AFM tip in contact with the centre of the denoted area, measured I–Vb curves shown in Fig. 2b reveal a decrease in current with increasing force and this decrease can be reversed when the strain was released. It can also be clearly seen that the measured current through the device at a fixed voltage (0.55 V) monotonically decreased as deformation increased, as shown in the inset of Fig. 2b.

Bottom Line: Here we report the experimental study of the theoretically predicted piezoelectric effect in triangle monolayer MoS2 devices under isotropic mechanical deformation.The underlying mechanism of strain-induced in-plane charge polarization is proposed and discussed using energy band diagrams.Our results provide evidence for strain-gating monolayer MoS2 piezotronics, a promising avenue for achieving augmented functionalities in next-generation electronic and mechanical-electronic nanodevices.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road 30, Beijing 100083, China.

ABSTRACT
High-performance piezoelectricity in monolayer semiconducting transition metal dichalcogenides is highly desirable for the development of nanosensors, piezotronics and photo-piezotransistors. Here we report the experimental study of the theoretically predicted piezoelectric effect in triangle monolayer MoS2 devices under isotropic mechanical deformation. The experimental observation indicates that the conductivity of MoS2 devices can be actively modulated by the piezoelectric charge polarization-induced built-in electric field under strain variation. These polarization charges alter the Schottky barrier height on both contacts, resulting in a barrier height increase with increasing compressive strain and decrease with increasing tensile strain. The underlying mechanism of strain-induced in-plane charge polarization is proposed and discussed using energy band diagrams. In addition, a new type of MoS2 strain/force sensor built using a monolayer MoS2 triangle is also demonstrated. Our results provide evidence for strain-gating monolayer MoS2 piezotronics, a promising avenue for achieving augmented functionalities in next-generation electronic and mechanical-electronic nanodevices.

No MeSH data available.


Related in: MedlinePlus