A CNT charge sensor with a single charged dot at the middle of the channel. (a) A schematic plot of the cross section of the modeled device. (b) The simulated channel conductance vs the gate voltage on log (left) and linear (right) scales for different amounts of charge on the dot, , at /step. (c) The first conduction and valence bands vs the position along the channel for at . The source and drain Fermi levels are set at . The diameter of the dot is .
(a) The simulated shift due to the single electron addition to the charged dot vs the bottom oxide thickness when the charged dot is modeled as a metallic ball (the solid line) and a uniformly charged ball (the dashed line). (b) Room temperature measurement of the CNT memory device right after charging (the curve on the left) and full discharging (the curve on the right). The subthreshold slope (dashed line) should be the same in both curves. The curve for the charged device, however, shows a series of threshold voltage shifts with magnitudes of whose direction suggests that these shifts are due to discharge events during measurements.
Position-dependent response of the sensor. (a) The channel conductance vs the position of the charged dot when for the device, as shown in Fig. 1(a). The dashed line shows the channel conductance with for reference. The first subband profile (the solid line) and the channel transmission vs energy (the dashed line) for (b) no charged dot, (c) a charged dot at , and (d) a charged dot at . The gate voltage and the drain voltage .
A CNT charge sensor with two charged dots. (a) The simulated device structure. (b) The channel conductance vs the position of dot 2 . Dot 1 is fixed at . The solid line is for , and the dashed line is for and . (c) The first subband profile (the solid line) and the channel transmission (the dashed line) for , , and . (d) The first subband profile and transmission for , , and . The gate voltage and the drain voltage . The charged dots are modeled as metallic balls.
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