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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