Nano-Newton transverse force sensor using a vertical GaN nanowire based on the piezotronic effect.

Semiconductor nanowires (NWs) have been researched as the building blocks for various nanosensors and devices, such as strain sensors, [ 1,2 ] photodetectors, [ 3 ] biosensors, [ 4 ] and gas sensors. [ 5 ] In recent years, wurtzite semiconductor NWs, such as ZnO, have been extensively investigated due to their piezoelectric properties. [ 6 ] With metal-semiconductor Schottky junctions, the electric transport through a NW can be modulated through external strain due to the piezotronic effect, using the polarization induced electric potential to tune the chargecarrier generation, transport, separation or recombination at a metal-semiconductor interface or a p-n junction. [ 6 ] The piezotronic effect has been used for fabricating various functional devices such as strain sensors, [ 1 ] piezoelectric switches, [ 7 ] electromechanical memory, [ 8 ] and strain-gated logic nanodevices. [ 9 ]