Optical properties of ferroelectric films Hf-=SUB=-x-=/SUB=-Zr-=SUB=-y-=/SUB=-O-=SUB=-2-=/SUB=- and La : Hf-=SUB=-x-=/SUB=-Zr-=SUB=-y-=/SUB=-O-=SUB=-2-=/SUB=- according to ellipsometry data

Abstract

Recently ferroelectric properties have been found in hafnia-based nanosized films. Such films are of the utmost interest for development of a universal memory, which combines the advantages of random access memory and flash memory. The paper studies optical properties of hafnia-zirconium oxide films HfxZryO2 and lanthanum-alloyed hafnia-zirconium oxide films La : HfxZryO2. Fluctuations of thickness in HfxZryO2 do not exceed 3.5%, fluctuations of thickness in La : HfxZryO2 films --- 3.2%. Optical properties are analyzed based on effective-medium theory. According to effective-medium theory data, HfxZryO2 films contain 46% HfO2, 54% ZrO2, La : HfxZryO2 films contain 47.5% HfO2, 52.4% ZrO2, 2.5% La2O3. Keywords: ferroelectric, refraction index, spectral ellipsometry, effective-medium theory.