Ferroelectric properties of HfO2 nanodots with a diameter smaller than 10 nm deposited on an ITO bottom electrode

Abstract

HfO2 nanodots and epitaxial HfO2 thin films with ferroelectric properties were grown on yttria-stabilized zirconia substrates with indium tin oxide bottom electrodes via a pulsed laser deposition (PLD) method. The crystallinity and ferroelectric properties of the epitaxial HfO2 thin films were analyzed to compare ferroelectric properties resulting from crystallinity and the strained structure of HfO2 nanodots. Using the total number of PLD pulses as a control, it was possible to grow HfO2 nanodots with diameters of 7, 12, and 20 nm and heights of 4.9, 7.8, and 14.8 nm. Based on the d33 piezoelectric hysteresis loops and polarization switching phenomena, it was confirmed that the HfO2 nanodots exhibited good ferroelectric properties even for scaling of less than 7 nm in diameter. The observation of the piezoelectric d33 hysteresis loop of the HfO2 nanodots and epitaxial HfO2 thin films revealed that HfO2 nanodots had improved ferroelectric properties due to the size effect.