Experimental and finite element method calculation of piezoelectric power generation from ZnO nanowire arrays grown on different substrates using high and low temperature methods

• In this paper we investigate the piezoelectric power generation from ZnO nanowire arrays grown using different methods. The ZnO nanowires are grown on n-SiC and n-Si substrates using both the high-temperature vapor liquid solid (VLS) and the lowtemperature aqueous chemical growth (ACG) methods. A conductive atomic force microscope (AFM) is used in contact mode to deflect the ZnO nanowire arrays. A piezoelectric potential across the nanowires is produced and then released via the rectifying behavior of the Schottky barrier at the platinum metal-ZnO interface. We do not observe any substrate effect but the growth method, crystal quality, density, length and diameter (aspect ratio) of the nanowires are found to affect the piezoelectric behavior. These parameters can significantly affect the performance manifested in the observed output voltage signal. Based on these parameters, we compare four nanogenerators under identical conditions. During the AFM scanning in contact mode without biased voltage, the ZnO nanowire arrays grown by the VLS method produce higher and larger output voltage signal of 35 mV compared to ZnO nanowires arrays grown by the ACG method, which produce smaller output voltage signal of 5 mV. We apply finite element (FE) method calculations to investigate the output voltage of ZnO nanowires based nanogenerators with different aspects ratios. From FE results we find that the output voltage of the nanogenerator is decreased above an aspect ratio 80 of ZnO nanowires.

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