Enhanced dielectric and energy storage performances of Hf0.6Zr0.4O2 thin films by Al doping

Hf- and Zr-based oxide thin films, which have various polarization characteristics depending on the crystal structure, have been intensively studied for application in various semiconductor devices due to their excellent electrical properties and complementary metal oxide semiconductor process compatibility. Especially, when the tetragonal phase is implemented, they exhibit a high dielectric constant with anti-ferroelectric properties. Therefore, in this study, the effect of Al doping in HfZrO2 thin films was investigated from the viewpoint of the realization of a high dielectric constant and a stable anti-ferroelectric phase. Through a small amount of Al doping, the crystal structure was modulated from monoclinic to tetragonal. Also, the polarization characteristics were observed in the change of ferroelectric to anti-ferroelectric. Owing to the formation of a tetragonal structure, the dielectric constant was improved up to 41, and the leakage current density remarkably decreased by more than one order of magnitude. Moreover, the Al-doped HfZrO2 thin film with anti-ferroelectricity exhibited excellent energy storage properties with an energy storage density and efficiency of about 53.3 J/cm3 and 76% at ±4.5 MV/cm, respectively. Therefore, we propose that Al-doped HfZrO2 thin film could be applied as a candidate material for next-generation charge storage devices.