The influence of Yttrium on leakage current and dielectric properties of amorphous Al₂O₃ thin film derived by sol–gel

Amorphous Yttrium-doped aluminum oxide thin films were deposited on Pt/Ti/SiO₂/Si substrates by sol–gel. It was observed by field emission scanning electron microscope that the surface morphology was smooth and homogeneous. From Fourier Transform Infrared Spectroscopy, a broad absorption band at 700–1000 cm⁻¹ owing to vibrations of aluminum oxide was observed. The absorption peaks strength relating to hydroxyl group decreased with the increase of Y doping concentration. The electrical properties were investigated in terms of Y doping content and relative humidity. The results show that the existence of hydroxyl and absorbed water makes a significant influence on the electric properties of films. The electric conduction characteristics and dielectric breakdown properties are modified by the decrease of content of hydroxyl and absorbed water, leading to a lower leakage current and higher dielectric strength. It can be seen that the leakage current of films decreases with the Y doping, and could be reasonably deduced that leakage current can be effectively tuned by Y doping.