Enhancing responsivity of ZnO nanowire based photodetectors by piezo-phototronic effect

•A promising approach was proposed to enhance the responsivity of a ZnO nanowires array based photodetector though piezo-phototronic effect.•The ZnO nanowires serve as piezoelectric functional layer and light-trapping material.•Using polarization charges at interfaces under strain, the local Schottky barrier height and the responsivity of the device can be modulated.•The fabricated detector allows simultaneous and identical changing behavior of Schottky barrier heights at the two contacts.

A promising approach was proposed to enhance the responsivity of a ZnO nanowires array based photodetector with metal-semiconductor-metal structure through piezo-phototronic effect. The ZnO nanowires arrays were synthesized via hydrothermal method to function as both piezoelectric and light-trapping layer. The photoresponses of the ZnO nanowires based photodetector were tuned by the modulation of local Schottky barrier heights (SBH) at the metal-ZnO interfaces as a result of strain-induced polarization charges. Subjected to a −0.62% compressive strain, the responsivity of the prepared photodetector was increased by as much as 176%. Furthermore, the devices hydrothermally synthesized at 0.10 M have a larger photoresponse and higher stress sensitivity compared to the ones prepared at 0.05 M and 0.15 M. This work not only strengthens the fundamental understanding of piezo-phototronic effect on photodetectors but also provides an efficient means for optimization/improvement of piezoelectric semiconductor nanowires based optoelectronic devices.

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