730 research outputs found
Band gap engineering of MoS upon compression
Molybdenum disulfide (MoS) is a promising candidate for 2D nanoelectronic
devices, that shows a direct band-gap for monolayer structure. In this work we
study the electronic structure of MoS upon both compressive and tensile
strains with first-principles density-functional calculations for different
number of layers. The results show that the band-gap can be engineered for
experimentally attainable strains (i.e. ). However compressive strain
can result in bucking that can prevent the use of large compressive strain. We
then studied the stability of the compression, calculating the critical strain
that results in the on-set of buckling for free-standing nanoribbons of
different lengths. The results demonstrate that short structures, or few-layer
MoS, show semi-conductor to metal transition upon compressive strain
without bucking
Nonlinear oscillators for vibration energy harvesting
Vibration to electricity energy conversion strategies are discussed by using nonlinear stochastic dynamics. General principles for the exploitation of nonlinear oscillators in energy harvesting that provide useful leads for the realization of micropower generators of practical interest are presented
Fast MoS 2 thickness identification by transmission imaging
AbstractDetermining the thickness of a few-layer 2D material is a tough task that often involves complex and time consuming measurements. Here we discuss a rapid method for determining the number of layers of molybdenum disulfide, MoS
2
, flakes based on microscopic transmission imaging. By analyzing the contrast of the red, blue and green channels of the flake image against the background, we show that it is possible to unequivocally determine the number of layers. The presented method is based on the light absorption properties of MoS
2
and its validity is confirmed by micro-Raman measurements. The main advantage of this method against traditional methods is to quickly determine the thickness of the material in the early stages of the experimental process with low cost apparatus
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