On analysis of optical and impedance spectroscopy properties of nickel tetraphenyl porphyrin nanostructure /ITO Schottky diodes

Abstract

Transparent conducting substrates (ITO) were utilized to fabricate Ni (II) Tetraphenyl Porphyrin/ITO optical systems by thermal evaporation technique. The characteristic parameters of the topological properties, such as the height profile of the surface roughness and the average height difference Ra = 32.4 nm. The deviation of the Hight distribution was found to be Rq = 4.8 nm. Also, there were five peaks with orientations (211), (222), (400), (440) and (622) belonging to ITO thin films. At wavelengths ≥1600 nm, the NiTPP films do not have any depicted influences on the transmittance of ITO. The Reflectance of ITO films was decreased due to the induced absorption of the NiTPP layer in visible and NIR regions. The estimated transitions between HOMO and LUMO levels were indirect for NiTPP films; the optical energy gap EopNiTPP=1.93eV and the second transition was the fundamental bandgap EgNiTPP=2.58eV. For ITO films, the transition was direct (EgITO=3.66eV). The Q-factor was investigated to declare the relationship between the stored energy and to dissipated one in the fabricated ITO/NiTPP/Al Schottky device. The uploaded applied D.C. voltage becomes more practical in shifting the value of the Q-factor towards the higher frequencies. The parallel conductance through the device reveals a mathematical relation: Gp ∼ ωn, where n is an exponent dependent on the conductance through the fabricated ITO/NiTPP/Al Schottky devices. The complex electric modulus examined the interfacing properties of the fabricated Al/NiTPP/ITO systems under applied D.C. voltage from −1.5 to 1.5 V and frequency ∼42Hz to 5 MHz and elucidated that the ITO-electrode is dominant. The uploaded D.C. voltage (from −1.5 to 1.5 V) on the oscillating applied voltage signal can control the induced electric dipoles through the fabricated ITO/NiTPP/Al Schottky devices.