Structural and functional properties of Al:ZnO thin films grown by Pulsed Laser Deposition at room temperature

Abstract

Current research on transparent conductive oxides (TCOs) is focusing on indium-free TCOs, such as Al-doped ZnO (AZO), as an alternative to indium–tin oxide. In this work, AZO thin films were grown by Pulsed Laser Deposition at room temperature in oxygen atmosphere. The O2 pressure was varied from 0.01Pa to 10Pa, highlighting the effects of defect formation and oxygen vacancies on the film properties. Structural properties were characterized by X-ray diffraction and Scanning Electron Microscopy, while functional properties were characterized by measurement of electrical conductivity, Hall mobility, carrier density and optical transmission. At an optimal deposition pressure of 2Pa, optical transparency in the visible range and minimum resistivity (4.5∙10−4Ωcm) were found, comparable to state-of-the-art TCOs. Mean value of visible transparency was shown to increase with increasing pressure, up to 88% at a deposition pressure of 10Pa.