Enhanced carrier separation assisted high-performance piezo-phototronic self-powered photodetector based on core-shell ZnSnO3 @In2O3 heterojunction

Abstract

Enhanced carrier separation and inbuilt electric field are recommended to demonstrate self-powered, high-performance photodetectors. Traditionally, planar, bulk, and vertical heterojunctions are used for fabrication of photodetectors.In this work, we demonstrate a self-powered piezo-phototronic photodetector using a unique coaxial n-n heterojunction i.e., ZnSnO3/In2O3 core-shell nanofibers synthesized using electrospinning. The detailed morphological characterization reveals the formation of ZnSnO3 core and In2O3 shell nanofiber while structural studies confirm the non-centrosymmetric cubic In2O3, with a space group of I213 and rhombohedral ZnSnO3 with R3c space group. The Piezo force microscopy (PFM studies displayed a piezoelectric coefficient (d33) value of the ZnSnO3/In2O3 nanofibers was obtained as 254 pm/V. The fabricated piezo-phototronic device displays a superior photo-response upon illumination of UV light at zero bias owing to the built-in electric potential. The optimized UV photodetector displayed a large Ion/Ioff ratio of 102. Upon application of a compressive strain of 4.3%, the device exhibits an increase in photocurrent up to 58% and upon the tensile strain of 3.2%, the device shows a decrease in photocurrent up to 24%. The obtained results can be attributed to the enhanced carrier separation in the coaxial interfaces of ZnSnO3/In2O3 junctions, thus improving the ability to detect UV light. The fabricated device exhibits a maximum responsivity and detectivity of 0.7 mA/W and 8.3 × 109 Jones respectively which are far superior to the existing class of similar devices fabricated using sophisticated cleanroom techniques Further, a stable photo-response even after 1000 bending cycles proves its mechanical robustness. This work provides a promising strategy for improving the responsivity and detectivity of photodetectors as well as a unique coaxial nanostructure for self-powered, UV light detection for optoelectronic applications.