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▲ [13p-D221-1] Strained induced ripples and structure change in MoS2 nanosheet
Keywords:Molybdenum disulfide, Strain, Rippled structure
In this work, we investigated the strain dependence of the periodic ripple structure formed in MoS2 nanosheet of several layers by using in-situ stretching transmission electron microscopy (TEM) observation. The structure change of mechanically exfoliated MoS2 nanosheet were observed at an atomic scale when increasing the strain by stretching uniaxially.
The ripple structure could be identified by the strain mapping which was retrieved from atomic-resolved TEM image of the MoS2 nanosheet by geometric phase analysis (GPA) method. We also found that contrast of the MoS2 nanosheet changed periodically along with the zigzag direction. Since the contrast change correlated with the strain mapping, it seems to be caused by the defocus difference. It means that the height is different between the regions showing different contrast and the MoS2 nanosheet form the ripple structures The strain tensor mappings, εxx and εyy, of the MoS2 nanosheet were obtained before stretching and after stretching by applying the bias voltage of 0.3 and 0.4 V. Before stretching, the ripple structure of the MoS2 nanosheets was formed one-dimensionally along the armchair direction. After stretching, we found that new two-dimensional strain distribution, corresponding to new two-dimensional ripple structure.
The ripple structure could be identified by the strain mapping which was retrieved from atomic-resolved TEM image of the MoS2 nanosheet by geometric phase analysis (GPA) method. We also found that contrast of the MoS2 nanosheet changed periodically along with the zigzag direction. Since the contrast change correlated with the strain mapping, it seems to be caused by the defocus difference. It means that the height is different between the regions showing different contrast and the MoS2 nanosheet form the ripple structures The strain tensor mappings, εxx and εyy, of the MoS2 nanosheet were obtained before stretching and after stretching by applying the bias voltage of 0.3 and 0.4 V. Before stretching, the ripple structure of the MoS2 nanosheets was formed one-dimensionally along the armchair direction. After stretching, we found that new two-dimensional strain distribution, corresponding to new two-dimensional ripple structure.