Effects of Bilayer Thickness on the Morphological, Optical, and Electrical Properties of Al2O3/ZnO Nanolaminates

This report mainly focuses on the investigation of morphological, optical, and electrical properties of Al2O3/ZnO nanolaminates regulated by varying bilayer thicknesses. The growth mechanism of nanolaminates based on atomic layer deposition and Al penetration into ZnO layer are proposed. The surface roughness of Al2O3/ZnO nanolaminates can be controlled due to the smooth effect of interposed Al2O3 layers. The thickness, optical constants, and bandgap information of nanolaminates have been investigated by spectroscopic ellipsometry measurement. The band gap and absorption edge have a blue shift with decreasing the bilayer thickness on account of the Burstein-Moss effect, the quantum confinement effect and the characteristic evolution of nanolaminates. Also, the carrier concentrations and resistivities are found to be modified considerably among various bilayer thicknesses. The modulations of these properties are vital for Al2O3/ZnO nanolaminates to be used as transparent conductor and high resistance layer in optoelectronic applications.