sajedeh manzeli - Academia.edu (original) (raw)
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Centro de Investigacion y Estudios Avanzados del IPN
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Papers by sajedeh manzeli
Nature Communications, 2015
Nanoelectromechanical systems constitute a class of devices lying at the interface between fundam... more Nanoelectromechanical systems constitute a class of devices lying at the interface between fundamental research and technological applications. Realizing nanoelectromechanical devices based on novel materials such as graphene allows studying their mechanical and electromechanical characteristics at the nanoscale and addressing fundamental questions such as electron-phonon interaction and bandgap engineering. In this work, we realize electromechanical devices using single and bilayer graphene and probe the interplay between their mechanical and electrical properties. We show that the deflection of monolayer graphene nanoribbons results in a linear increase in their electrical resistance. Surprisingly, we observe oscillations in the electromechanical response of bilayer graphene. The proposed theoretical model suggests that these oscillations arise from quantum mechanical interference in the transition region induced by sliding of individual graphene layers with respect to each other. Our work shows that bilayer graphene conceals unexpectedly rich and novel physics with promising potential in applications based on nanoelectromechanical systems.
Nano Letters, 2015
Continuous tuning of material properties is highly desirable for a wide range of applications, wi... more Continuous tuning of material properties is highly desirable for a wide range of applications, with strain engineering being an interesting way of achieving it. The tuning range is however limited in conventional bulk materials which can suffer from plasticity and low fracture limit due to the presence of defects and dislocations. Atomically thin membranes such as MoS 2 on the other hand exhibit high Young's modulus and fracture strength which makes them viable candidates for modifying their properties via strain. The bandgap of MoS 2 is highly strain-tunable which results in the modulation of its electrical conductivity and manifests itself as the piezoresistive effect while a piezoelectric effect was also observed in odd-layered MoS 2 with broken inversion symmetry. This coupling between electrical and mechanical properties makes MoS 2 a very promising material for nanoelectromechanical systems (NEMS). Here we incorporate monolayer, bilayer and trilayer MoS 2 in a nanoelectromechanical membrane configuration. We detect strain-induced band gap tuning via electrical conductivity measurements and demonstrate the emergence of the piezoresistive effect in MoS 2. Finite element method (FEM) simulations are used to quantify the band gap change and to obtain a comprehensive picture of the spatially varying bandgap profile on the membrane. The piezoresistive gauge factor is calculated to be −148 ± 19, −224 ± 19 and −43.5 ± 11 for monolayer, bilayer and trilayer MoS 2 respectively which is comparable to state-of-the-art silicon strain sensors and two orders of magnitude higher than in strain sensors based on suspended graphene. Controllable modulation of resistivity in 2D nanomaterials using strain-induced bandgap tuning offers a novel approach for implementing an important class of NEMS transducers, flexible and wearable electronics, tuneable photovoltaics and photodetection.
Nature Communications, 2015
Nanoelectromechanical systems constitute a class of devices lying at the interface between fundam... more Nanoelectromechanical systems constitute a class of devices lying at the interface between fundamental research and technological applications. Realizing nanoelectromechanical devices based on novel materials such as graphene allows studying their mechanical and electromechanical characteristics at the nanoscale and addressing fundamental questions such as electron-phonon interaction and bandgap engineering. In this work, we realize electromechanical devices using single and bilayer graphene and probe the interplay between their mechanical and electrical properties. We show that the deflection of monolayer graphene nanoribbons results in a linear increase in their electrical resistance. Surprisingly, we observe oscillations in the electromechanical response of bilayer graphene. The proposed theoretical model suggests that these oscillations arise from quantum mechanical interference in the transition region induced by sliding of individual graphene layers with respect to each other. Our work shows that bilayer graphene conceals unexpectedly rich and novel physics with promising potential in applications based on nanoelectromechanical systems.
Nano Letters, 2015
Continuous tuning of material properties is highly desirable for a wide range of applications, wi... more Continuous tuning of material properties is highly desirable for a wide range of applications, with strain engineering being an interesting way of achieving it. The tuning range is however limited in conventional bulk materials which can suffer from plasticity and low fracture limit due to the presence of defects and dislocations. Atomically thin membranes such as MoS 2 on the other hand exhibit high Young's modulus and fracture strength which makes them viable candidates for modifying their properties via strain. The bandgap of MoS 2 is highly strain-tunable which results in the modulation of its electrical conductivity and manifests itself as the piezoresistive effect while a piezoelectric effect was also observed in odd-layered MoS 2 with broken inversion symmetry. This coupling between electrical and mechanical properties makes MoS 2 a very promising material for nanoelectromechanical systems (NEMS). Here we incorporate monolayer, bilayer and trilayer MoS 2 in a nanoelectromechanical membrane configuration. We detect strain-induced band gap tuning via electrical conductivity measurements and demonstrate the emergence of the piezoresistive effect in MoS 2. Finite element method (FEM) simulations are used to quantify the band gap change and to obtain a comprehensive picture of the spatially varying bandgap profile on the membrane. The piezoresistive gauge factor is calculated to be −148 ± 19, −224 ± 19 and −43.5 ± 11 for monolayer, bilayer and trilayer MoS 2 respectively which is comparable to state-of-the-art silicon strain sensors and two orders of magnitude higher than in strain sensors based on suspended graphene. Controllable modulation of resistivity in 2D nanomaterials using strain-induced bandgap tuning offers a novel approach for implementing an important class of NEMS transducers, flexible and wearable electronics, tuneable photovoltaics and photodetection.