Physical property improvement of IZTO thin films using a hafnia buffer layer

Hafnia (HfO2) has excellent mechanical and chemical stability, good transmittance, high dielectric constant, and radiation resistance property; thus, it can prevent impurities from permeating into the depositing films. So, we deposited hafnia films with various thicknesses in the range of 0–60 nm on polyethylene naphthalate (PEN) substrates before depositing indium–zinc–tin oxide (IZTO) thin films on them using RF magnetron sputtering, and their structural, morphological, optical, and electrical properties were evaluated. All IZTO thin films were successfully deposited without cracks or pinholes and had amorphous structures. As the thickness of the hafnia film increased to 30 nm, the overall properties improved; a surface roughness of 2.216 nm, transmittance of 82.59% at 550 nm, resistivity of 5.66 × 10−4 Ω cm, sheet resistance of 23.60 Ω/sq, and figure of merit of 6.26 × 10−3 Ω−1 were realized. These results indicate that the structure and materials studied in this research are suitable for application in flexible transparent electronic devices such as organic light emitting diodes, liquid crystal displays, touch panels, and solar cells.