Optical, structural, and morphological characterisation of epitaxial ZnO films grown by pulsed-laser deposition

• This study examines the quality of ZnO layers deposited by pulsed laser deposition.
• Effects of temperature, oxygen pressure, and type of substrate are shown.
• Photoluminescence, X-ray diffraction, and atomic force microscopy measurements made
• In terms of costs, sapphire substrates are the best candidates for epitaxial growth.

We report on ZnO epitaxial growth by pulsed-laser deposition (PLD) on different substrates, such as quartz, sapphire, and GaN template. Approximately 1 μm-thick films were grown under different substrate temperatures and background oxygen conditions. X-ray diffraction analysis indicated preferential growth along the c-axis direction with a full-width at half maximum (FWHM) of the rocking curve as narrow as 230 arcs in the case of the GaN template. Low-temperature photoluminescence showed A-excitonic emission near 3.36 eV and a FWHM of D0XA emission as small as 2.89 meV at 9 K. Atomic force microscope measurements showed that roughness as low as 18 nm could be obtained. These results prove that PLD is a low-cost technique suitable to grow heteroepitaxial ZnO layers with excellent properties in terms of luminescence, crystallinity and morphology.