Fig. 4

Examples of how different commonly used transport mechanisms can be fitted convincingly to the same measured IV curve and several regions overlap to the extent that it is impossible to make a conclusion only based on the curve fitting. The equations underlying the fits are the standard textbook equations for the respective models and the measured IV curve is from a system like [36]. a, b Schottky emission model, linearized fits and actual IV curve with overlaid fits. c, d Same for Poole–Frenkel emission. Note that for the x-axis for c, the negative values are −|V|^1/2. The fitted areas fit just as well as with the Schottky emission model. e, f Linearized piece-wise fits for the space-charge-limited conduction (SCLC) model and g for the trap-assisted tunnelling (TAT) model. The TAT fits for the negative voltages are not shown due to limited figure space. h, i Measured IV curves with overlaid fitting results from e–g