Taper PbZr0.2Ti0.8O3 Nanowire Arrays: From Controlled Growth by Pulsed Laser Deposition to Piezopotential Measurements

Single crystalline PbZr0.2Ti0.8 (PIT) nanowires arrays (NWAs) with taper morphology were epitaxially grown on SrTiO3 (STO) substrate using pulse laser deposition. The taper morphology was attributed to the overcoating of PIT layer via a lateral growth of Pit clusters/adatoms during PIT NW growth.. The growth window for PZT film or nanowire was systematically studied at varied temperatures and pressures. The proposed growth mechanism of the taper PIT NWAs was investigated from a layer by layer growth via Frank-Van Der Merwe growth, followed by a formation of three-dimensional islands via Stranski-Krastanow growth, and then axial growth on the lowest energy (001) plane with growth direction of [001] via vapor-solid growth mechanism. However, under certain conditions such as at higher or lower pressure (>400 or <200 mTorr) or substrate temperatures (>850 degrees C and <725 degrees C), formation of the PIT NWs is suppressed while the epltaxial Pit thin film via the layer-by-layer growth remains. The controllable growth directions of the PZT NWAs on (001), (110), and (111) STO substrates were demonstrated. The piezopotential of the taper PIT NWAs using a conducting atomic force microscope with the average voltage output of similar to 18 mV was measured. The theoretical piezopotential of a PIT NW was calculated to compare with the measured outputs, providing a comprehensively experimental and theoretical understanding of the piezoelectricity for the PZT NW.