Piezotronic effect enhanced detection of flammable/toxic gases by ZnO micro/nanowire sensors

Compared with conventional Ohmic-contact nanosensors, Schottky-contact has been introduced as a fundamentally new design for much enhanced sensitivity and improved responsive time of one-dimensional nanostructure based sensors. Here we demonstrate ZnO micro/nanowire sensors for hydrogen (H₂) and nitrogen dioxide (NO₂) detections at room-temperature based on a metal-semiconductor-metal (M-S-M) structure. By utilizing strain-induced piezoelectric polarization charges presented at the vicinity of local interface to modify the band structure at Schottky contact, piezotronic effect has been introduced to gate/modulate the charge carriers transport process across the M-S contact and thus hugely enhance/optimize the performances of H₂/NO₂ gas sensors. Upon straining, the detection sensitivity and resolution are obviously improved, together with a significant enhancement in output current by 5359% for H₂ and 238.8% for NO₂ detection. This work provides a promising approach to raise the sensitivity, improve the detection resolution, and generally enhance the performance of gas sensing, making it possible for fabricating room temperature of gas sensor while preserving its sensitivity.