Ultrasensitive Strain Sensor Based on a Tunnel Junction with an AlN/GaN Core-Shell Nanowire

Piezotronic transistor operating in the quantum tunneling regime has recently roused wide interest for developing ultrasensitive strain sensing with applications in wearable electronics and human-machine interfaces. However, the lack of a strict theoretical demonstration from a quantum perspective renders the development of such an emerging area particularly slow due to their complex fabrication process and vulnerable experimental interference. Here, by combining third-dimensional self-consistent calculation with a nonequilibrium Green's function framework, we study the intrinsic device properties of piezotronic tunneling transistor (PTT) based on AlN/GaN core-shell nanowire. The results show that strain-induced piezoelectric polarization can remarkably tune tunneling barrier height and width, both of which are increased by tensile strain and decreased by compressive strain. At a moderate strain amplitude of 1.0% and bias of 2.0 V, the strain-induced change in effective barrier height and width can reach as high as 0.5 eV and 4.0 nm, respectively. This remarkable tunability in the barrier allows for an ultrahigh on/off current ratio 1017, and giant gauge factor 1.2 x 108 in current and 1.1 x 1013 in resistance. The performance can be further optimized by properly tailoring device architectures, including insulator thickness, nanowire length, or core-shell size. Our demonstration of the PTT with combined quantum tunneling and piezotronic effect opens a window for designing highly sensitive, large on/off ratio and low-power strain sensing.

Automated summary

By combining third-dimensional self-consistent calculation with a nonequilibrium Green's function framework, this study investigates the intrinsic device properties of piezotronic tunneling transistor based on AlN/GaN core-shell nanowire. The results demonstrate that strain-induced piezoelectric polarization can significantly tune tunneling barrier height and width. At a moderate strain amplitude of 1.0% and bias of 2.0 V, the strain-induced change in effective barrier height and width can reach as high as 0.5 eV and 4.0 nm, respectively. This tunability allows for an ultrahigh on/off current ratio and giant gauge factor in current and resistance.