G.P. Anggraeni, A. Saripudin, A. Rusydi, Y. Darma
Vertically arranged columnar TiO2:Co structure has been deposited on Si (100) substrate using the metal organic chemical vapor deposition (MOCVD) technique. SEM images confirm the columnar structure of the TiO2:Co layer on Si (100). Concentration of the Co dopant has been defined by means of the energy dispersive x-ray (EDX) spectra. Co concentrations are varied at 0.18, 0.33, and 0.68 at. % using pure TiO2 as the reference. X-ray diffraction (XRD) spectra show that the TiO2:Co layer have a rutile phase. Further analysis of this structure has been performed by using room temperature spectroscopic ellipsometry (SE) measurements in the energy range of 0.5 - 6.5 eV. This optical response shows the unique feature of significantly high density fringe especially below the band gap energy region (lower than 3.3 eV) in contrast to the conventional TiO2 thin film structure. This unique feature is interpreted as a dominant contribution of the vertical interfaces at columnar boundaries towards reflected light from the sample. The evolution of Ψ and Δ will be discussed as the function of Co concentration and some optical properties will be extracted after reasonably well data fitting by multilayer modelling. Furthermore, by comparing the SE data from different measurement orientations, it has been shown that TiO2:Co tends to be anisotropic. This study enables us to further evaluate structural properties through optical responses given by SE measurement. © 2015 AIP Publishing LLC.
Department of Physics, Institut Teknologi Bandung, Ganesha 10, Bandung, 40132, Indonesia; Department of Physics, Universitas Pendidikan Indonesia, Setiabudi 229, Bandung, 40154, Indonesia; Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore; NUSNNI-Nanocore, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
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