Effects of the AlN buffer layer thickness on the properties of ZnO films grown on c-sapphire substrate by pulsed laser deposition

Abstract

In this work, ZnO films with high crystal quality were grown by pulsed laser deposition (PLD) on different c-plane AlN/c-sapphire template thereby the thicknesses of AlN buffer layers varied from 150 to 300nm. The properties of ZnO thin films were studied by using high-resolution X-ray diffraction, atomic force microscopy, photoluminescence spectroscopy, and Raman measurement. The comparative investigation results show that inserting an AlN buffer layer is an effective way to improve the crystal quality of ZnO films. Furthermore, the thickness of the AlN buffer layer plays an important role on the quality of ZnO films. The result of (0002) ω-rocking curve with the full width at half maximum (FWHM) of 0.09° indicates that high-quality c-plane ZnO films can be achieved by using a 150nm-thickness AlN/c-sapphire template. In the best knowledge of the authors, this is the minimum value reported at present for ZnO films grown on AlN/c-sapphire templates by PLD.