Figure 3.
Intra-CNT (semiconducting) sensing mechanism through changes in charge carrier concentration or mobility. Hypothetical transfer (I-Vg) curves and band diagrams before (black) and after (red) the exposure to the analyte for three different sensing mechanisms. The dotted line in the band diagram corresponds to the metal work function of the electrode and diagrams are given for both p- and n-type semiconductors interfaces with a metal. (a) n-Doping of the CNT induces a shift of the I-V curve to more negative voltages. The band diagram shows a hole doped CNT. (b) Schottky barrier modulation corresponds to a change of the barrier height between the work function of the metal electrode and CNT and asymmetric change in conductance for electron and hole transport. The band diagram shows change in barrier height for hole transport. (c) Change in mobility can be induced by the addition of resistive elements or carrier scattering which reduces the conductivity in both p- and n-type materials. Inspired by Ref. 53.