Fig. 3: Piezotronic modification on the tunneling barrier height and width.
From: Highly sensitive strain sensors based on piezotronic tunneling junction
a Five cycles of current response to continuously changed tensile strain. The currents first increase rapidly and then slowly with increasing strain. b Energy band profile of tunneling junction. The metal/insulator/piezoelectric semiconductor tunneling barrier equivalent to a rectangular barrier, whose effective height and width are (BH)eff and (BW)eff, respectively, and their corresponding strain-induced changes are denoted as (ΔBH)eff and (ΔBW)eff. The part in ln(Istrain/Ifree) that has a linear relationship with strain is induced by the change of barrier height (ΔBH)eff. c ln(Istrain/Ifree) as a function of strain. The regions that change drastically (blue region, strain <0.01%) and slowly (red region, strain >0.02%) with strain correspond to different dominant mechanisms: the former is dominated by (ΔBW)eff, and the latter is dominated by (ΔBH)eff, both of which caused by the piezotronic effect. d Change of the effective barrier height and width derived from c as a function of applied strain.
