Preparation and electrical properties of ZnO/PZT films by radio frequency reactive magnetron sputtering

ZnO/PZT films have been continuously deposited on SiO2/Si substrate by radio frequency reactive magnetron sputtering method. The X-ray diffraction results showed that the ZnO thin films had a perfect c-axis preferred orientation, and the calculated press stress of the ZnO films was 0.67 GPa. Atomic force microscopy displayed that the microstructure of the PZT films was composed of small and uniform crystalline grains though there was a small quantity of pits. The root-mean square surface roughness was 4 nm. However, the ZnO films showed a dense, uniform and crack-free uniform microstructure. The average grain size and RMS surface roughness of the ZnO layers were, respectively, 50 nm and 2 nm. The scanning electron microscopy images showed that the ZnO films were composed of fine grains and exhibited the ball-like cluster morphology, and there was no clear interface between the ZnO and PZT films. The current–voltage curves of the ZnO/PZT heterostructure showed a good insulating characteristic.

► Highly c-axis oriented ZnO films were grown on PZT films using RF sputtering.
► The ZnO films showed a small FWHM and RMS surface roughness.
► The electrical properties of ZnO/PZT films were studied upon I–V curves.
► The ZnO/PZT composite films showed a good insulating characteristic.
► The transport properties of ZnO/PZT films were similar to the MFS structure.