Effect of Doping Carbon Nanotubes with Magnesium Oxide on its Structural and Optical Properties and Used in Diode Multilayers

Abstract

Carbon nanotube is long thin cylinders of graphite, it is made up of layers of carbon atoms every atom is connected evenly to three carbons arranged in a hexagonal lattice. In this research carbon nanotubes (CNTs) doping by magnesium oxide in different ratio (0.1, 0.3, 0.5, 0.7and 0.9) from soot and coal, were synthesized using thermal chemical vapour deposition (CVD), and used in diode Multilayers fabrication. Five samples of CNTs prepared from each source were doped by magnesium oxide in different ratio (0.1, 0.3, 0.5, 0.7and 0.9). X-ray diffraction technique (XRD) was used to obtain crystal structure and lattice parameters of samples, UV-Visible used to evaluate the optical properties.Fourier Transform Infrared spectroscopy (FTIR) used to measure the vibrational frequencies of bonds in the molecules. XRD results showed that the increasing in concentration of magnesium oxide leads to change structure parameter of carbon nanotubes samples (grain size, d-space, density and miller indices) FTIR showed different vibrational frequencies for CNTs from soot and coal, also showed that CNTs from coal more stable than CNTs from soot. For the optical properties the absorbance of CNTs from soot greater than CNTs from coal, for Soot samples the decrease of absorption at wavelengths 317 nm corresponding photon energy 3.912 eV by MgO concentration increase, and for Coal samples decrease at wavelengths 272 nm corresponding photon energy 4.559 eV by MgO concentration increase. The optical energy band gap decrease with MgO concentration increase, the optical band gap for soot and coal of CNTS within range of semiconductor materials (3.392-3.517) eV. Finally, the I-V Curve display that the samples are diode multilayer the charge injection voltage and turn off voltage increases when the concentration of MgO and number of layer increases for CNTS made from soot and coal. These results confirm the previous studies.