CNT-based field effect transistor (CNT-FET) including two palladium electrodes connecting the CNT for source-drain current measurements (ISD) as well as a back gate voltage control (VG). (a) Sketch of the device. (b) Scanning electron microscopy image of the substrate surface showing the studied individual CNT before being contacted by the as drawn electrodes. (c) Atomic force microscopy image of the region indicated by the blue arrow in (b), the diameter measured is 2.4 ± 0.2 nm.
Characterization of the CNT-FET under ambient conditions in air. (a) Raman spectra in the G-phonon region measured for excitation wavelengths 473 nm (blue line) and 633 nm (red line). (inset) Radial breathing modes observed at 210 cm−1 and 203 cm−1 for excitations 473 nm and 633 nm, respectively. (b) Transistor response showing p-doping in air, and hysteresis arising from charge traps below the nanotube.
Pressure evolution of the CNT-FET characteristics. Each ISD-VG curve is current-shifted for clarity. The black arrows indicate the direction in which the gate voltage is swept. Black squares and red dots locate the position of the current minima for gate voltage up-sweep and down-sweep . Red dashed lines: example of linear fits performed to extract the effective electron and hole mobilities.
Analysis of the metallic CNT resistance behaviour under pressure, extracted from the OFF-state transistor characteristics in Fig. 3 . Filled and open symbols account for pressure increase and decrease, respectively. Dashed lines are linear fits in three pressure regions.
Evolution of the gate voltage hysteresis under pressure. (left) Gate voltage of the OFF-state in Fig. 3 . Filled and open symbols refer to pressure increase and decrease, respectively. (right) Hysteresis amplitude .
Pressure dependence of the electron and hole effective mobilities in the CNT-FET device. Mobilities are extracted from linear fitting of the ISD-VG curves as shown in Fig. 3 .
Analysis of the p and n branches of the transistor characteristics under pressure via the evolution of currents at +10 and −10 V. (inset) Difference between ISD (VG = −10 V) and ISD (VG = +10 V). Filled and open symbols represent measurements during upstroke and downstroke, respectively.
CNT-FET in the Coulomb blockade regime at high pressure (4.5kbar). Color map of the current ISD as a function of the source-drain voltage VSD and gate voltage VG.
Observation of Coulomb blockade in an individual carbon nanotube bundle at low and high pressure (20 and 1560 bar). (a) Color map of the current ISD as a function of the source-drain voltage VSD and gate voltage VG, showing clear Coulomb diamonds at 20 bar. (b),(c) ISD-VG curve showing periodic current peaks for VSD = 3 mV. In this range of gate voltage, the periods at 20 bar and 1560 bar are 57 ± 6 mV and 55 ± 4 mV, respectively.
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