Figure 4
Dependence of force-current for LLM-105 nanosheets on HOPG substrate.
(a) logarithm of the curren of LLM-105 nanosheet as a function of applied bias at tip load of 0.2 nN, 1.5 nN, 3.0 nN, 6 nN and 7.5 nN. It shows the conductivity of the nanosheets was increased exponentially with the force. (b) The force-current experimental data (symbols) and theoretical fits (solid lines) at a constant bias of 0.5 V. A relation curve is drawn on the base of the currents at 30 different loads from 150 pN to 9.2 nN. The curve fits well with the calculating model described in text. It indicates that the calculating model is accurate and reliable and a load below 150 pN can be calculated by the model. (c) A SEM image of a typical gold-coated tip with an end radius of about 40 nm (the scale bar is 300 nm). (d) Schematic of the measurement architecture, the 154° nitro group will twist under tip load, resulting the conductivity of the nanosheet increase. When tip force is applied on LLM-105 nanosheet, the 154° nitro groups will rotate anticlockwise, the sheet will move toward HOPG and make the sheet thinner and current increase.
