RESUMO
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.
RESUMO
The tuning of structural, optical, and electrical properties of Al-doped ZnO films deposited by atomic layer deposition technique is reported in this work. With the increasing Al doping level, the evolution from (002) to (100) diffraction peaks indicates the change in growth mode of ZnO films. Spectroscopic ellipsometry has been applied to study the thickness, optical constants, and band gap of AZO films. Due to the increasing carrier concentration after Al doping, a blue shift of band gap and absorption edge can be observed, which can be interpreted by Burstein-Moss effect. The carrier concentration and resistivity are found to vary significantly among different doping concentration, and the optimum value is also discussed. The modulations and improvements of properties are important for Al-doped ZnO films to apply as transparent conductor in various applications.
