Characterization of amorphous aluminium oxide thin films synthesized by mist-CVD

Abstract

With its wide-bandgap (~7 eV), high breakdown field (~10 MV/cm) and high dielectric constant (~9) amorphous aluminum oxide (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) film is an attractive material for applications as gate insulator and/or surface passivation layers for electrical devices. Using several vacuum deposition techniques, such as sputtering, metal organic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD), high-quality Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin films have been reportedly obtained. One alternative approach to obtain high-quality Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin films is the mist chemical vapor deposition (mist-CVD), which can deposit various metal oxide thin films from relative non-toxic and nonpyrophoric aqueous solution, resulting in relatively simple and low-cost. In this study, we report on the deposition of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin films by atmospheric pressure solution-processed mist chemical vapor deposition (mist-CVD) technique at 400 °C and subsequent investigation of the chemical properties, crystallinity, bandgap, mass density and refractive index of the deposited films. We confirmed that the obtained values are comparable to those reported for high-quality amorphous Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin films deposited by ALD.