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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

Electromechanical behaviour of a MoS2 device under compressive and tensile strain.I–Vb characteristics of the MoS2 device at different applied forces under compressive (a) and tensile (b) strain when applying forces at locations denoted in upper insets resulting in compressive/tensile strain as shown schematically in lower insets. (c) The relation of loading location to tensile/compressive strain, where experimental observations indicate that the MoS2 monolayer undergoes tensile strain when force is applied near the edges (yellow circles) versus compressive strain when applied at the centre (green crosses). (d) The derived change of the Schottky barrier height as a function of strain at a bias voltage of 1 V.
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f4: Electromechanical behaviour of a MoS2 device under compressive and tensile strain.I–Vb characteristics of the MoS2 device at different applied forces under compressive (a) and tensile (b) strain when applying forces at locations denoted in upper insets resulting in compressive/tensile strain as shown schematically in lower insets. (c) The relation of loading location to tensile/compressive strain, where experimental observations indicate that the MoS2 monolayer undergoes tensile strain when force is applied near the edges (yellow circles) versus compressive strain when applied at the centre (green crosses). (d) The derived change of the Schottky barrier height as a function of strain at a bias voltage of 1 V.

Mentions: To better understand the origin of mechanical tuning of electronic properties in these devices, transport behaviours were compared by applying the mechanical force at distinct spatial locations on the MoS2 monolayer. Figure 4a,b provides the corresponding I–Vb curves measured at two fixed S–D electrodes, but with the AFM tip in contact at the centre and near the edge of the triangular film, respectively. The results reliably revealed a decrease in the measured current with increasing force applied at the centre (upper inset of Fig. 4a), but an increase in measured current with increasing force applied near the edge (upper inset of Fig. 4b) in all MoS2 monolayer devices. It was anticipated that both tensile and compressive strain result from localized deformation of the MoS2 monoloayer. The relation between spatially defined deformation and tensile/compressive strain was examined by positioning the AFM tip at various positions across the device as shown in Fig. 4c. The film can be imagined to be concave under compressive strain when a mechanical load is applied to the central region of the device (lower inset of Fig. 4a), whereas the surface is convex under tensile strain due to deformation near the edges (lower inset of Fig. 4b). These two different conditions of deformation position result in two bending cases of the film. According to experimental observations and our interpretation, tensile strain was observed by applying a mechanical load outside the dashed-line triangle region at points indicated by yellow circles in Fig. 4c. In contrast, compressive strain occurred when the contact region was inside the dashed-line triangle shape as indicated by green crosses. These observations strongly suggest that the film can be reliably switched between states of compressive and tensile strain.


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)

Electromechanical behaviour of a MoS2 device under compressive and tensile strain.I–Vb characteristics of the MoS2 device at different applied forces under compressive (a) and tensile (b) strain when applying forces at locations denoted in upper insets resulting in compressive/tensile strain as shown schematically in lower insets. (c) The relation of loading location to tensile/compressive strain, where experimental observations indicate that the MoS2 monolayer undergoes tensile strain when force is applied near the edges (yellow circles) versus compressive strain when applied at the centre (green crosses). (d) The derived change of the Schottky barrier height as a function of strain at a bias voltage of 1 V.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Electromechanical behaviour of a MoS2 device under compressive and tensile strain.I–Vb characteristics of the MoS2 device at different applied forces under compressive (a) and tensile (b) strain when applying forces at locations denoted in upper insets resulting in compressive/tensile strain as shown schematically in lower insets. (c) The relation of loading location to tensile/compressive strain, where experimental observations indicate that the MoS2 monolayer undergoes tensile strain when force is applied near the edges (yellow circles) versus compressive strain when applied at the centre (green crosses). (d) The derived change of the Schottky barrier height as a function of strain at a bias voltage of 1 V.
Mentions: To better understand the origin of mechanical tuning of electronic properties in these devices, transport behaviours were compared by applying the mechanical force at distinct spatial locations on the MoS2 monolayer. Figure 4a,b provides the corresponding I–Vb curves measured at two fixed S–D electrodes, but with the AFM tip in contact at the centre and near the edge of the triangular film, respectively. The results reliably revealed a decrease in the measured current with increasing force applied at the centre (upper inset of Fig. 4a), but an increase in measured current with increasing force applied near the edge (upper inset of Fig. 4b) in all MoS2 monolayer devices. It was anticipated that both tensile and compressive strain result from localized deformation of the MoS2 monoloayer. The relation between spatially defined deformation and tensile/compressive strain was examined by positioning the AFM tip at various positions across the device as shown in Fig. 4c. The film can be imagined to be concave under compressive strain when a mechanical load is applied to the central region of the device (lower inset of Fig. 4a), whereas the surface is convex under tensile strain due to deformation near the edges (lower inset of Fig. 4b). These two different conditions of deformation position result in two bending cases of the film. According to experimental observations and our interpretation, tensile strain was observed by applying a mechanical load outside the dashed-line triangle region at points indicated by yellow circles in Fig. 4c. In contrast, compressive strain occurred when the contact region was inside the dashed-line triangle shape as indicated by green crosses. These observations strongly suggest that the film can be reliably switched between states of compressive and tensile strain.

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