Figure 3.

Physical principles of tri‐channel transistor sensors. A) Transfer current–voltage characteristics of tri‐channel transistor sensors obtained from experiment and modeling using COMSOL Multiphysics. The applied drain voltage (V D) was +3 V, and the subthreshold regions are indicated in gray. B–F) Corresponding COMSOL simulations showing the electron density distributions along the cross‐section of the In2O3/ZnO heterostructure under the source and drain electrodes (labeled as S and D, respectively) and the electron flow streamlines within the channel regions, with different gate voltages (V G) applied: B) −1 V; C) 0 V; D) 1 V; E) 8 V; F) 20 V, and a constant V D = 3 V. G) Modeled transfer current–voltage characteristics (V D = 3 V) for baseline and under the exposure of simulated surface‐charged analytes. H–L) Corresponding COMSOL electron density distributions under the influence of simulated analytes when applying V D = 3 V and H) V G = −1 V; I) V G = 0 V; J) V G = 1 V; K) V G = 8 V; L) V G = 20 V to the transistor sensors. The electrodes and analytes are shown to indicate their positions with respect to the devices.