Atomic layer deposition of HfO2 on graphene from HfCl4 and H2O

• Published in: Central European journal of physics 2011-04, Vol.9 (2), p.319-324
• Main Authors: Alles, Harry, Aarik, Jaan, Aidla, Aleks, Fay, Aurelien, Kozlova, Jekaterina, Niilisk, Ahti, Pärs, Martti, Rähn, Mihkel, Wiesner, Maciej, Hakonen, Pertti, Sammelselg, Väino
• Format: Article
• Language: English
• Subjects: atomic layer depostion; Biological and Medical Physics; Biophysics; Environmental Physics; Geophysics/Geodesy; graphene; high-k dielectric thin films; nanoelectronics; Physical Chemistry; Physics; Physics and Astronomy; Research Article
• ISSN: 1895-1082; 2391-5471; 1644-3608; 2391-5471
• DOI: 10.2478/s11534-010-0040-x

Atomic layer deposition of HfO 2 on unmodified graphene from HfCl 4 and H 2 O was investigated. Surface RMS roughness down to 0.5 nm was obtained for amorphous, 30 nm thick hafnia film grown at 180°C. HfO 2 was also deposited in a two-step temperature process where the initial growth of about 1 nm at 170°C was continued up to 10–30 nm at 300°C. This process yielded uniform, monoclinic HfO 2 films with RMS roughness of 1.7 nm for 10–12 nm thick films and 2.5 nm for 30 nm thick films. Raman spectroscopy studies revealed that the deposition process caused compressive biaxial strain in graphene, whereas no extra defects were generated. An 11 nm thick HfO 2 film deposited onto bilayer graphene reduced the electron mobility by less than 10% at the Dirac point and by 30–40% far away from it.