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Investigation of the sensing mechanism in cobalt doped ZnO matrix based on structural, morphology, optical and electrical studies

A. ZIA1,2,* , S. AHMED3, N. A. SHAH4


  1. Government Postgraduate College Asghar Mall, Rawalpindi, Pakistan
  2. Center for Emerging Sciences, Engineering & Technology (CESET), Islamabad, Pakistan
  3. Advanced Electronics Laboratories, International Islamic University, Islamabad, Pakistan
  4. COMSATS, Institute of Information Technology (CIIT), Islamabad, Pakistan


The effective role of successive cobalt doping with co-precipitation route in ZnO matrix has been explored to study the presence of sensing response on the basis of its structural, morphological, optical and electrical characterization. X-ray diffraction (XRD) analysis confirms the incorporation of Cobalt in the ZnO matrix quite effectively. The increased bond length Zn-O in (002) plane on cobalt addition corresponds to an increase in the volume of unit cell. Scanning Electron Microscopy (SEM) provides further insight to the morphological features of the cobalt doped ZnO nanoparticles having spherical shape of increased dimensions. Fourier Transform infrared (FTIR) Spectroscopy reveals the incorporation of cobalt along with the presence of functional chemical bonding in the ZnO matrix. The observed peaks ranging from 1200- 1700 cm-1 correspond to Zn-OH bonding mode. The red shifted optical energy band gap is used to estimate the refractive index and found to be of small value in pure ZnO than the cobalt doped samples. An in-depth electrical characterization with two and four probe techniques provides an increase in the sheet resistance and resistivity with cobalt addition. Secondly, the reduction in photo electric resistance proves the existence of sensing mechanism in ZnO matrix. The variation in Hall mobility and voltage confirms the extrinsic semiconductor character of ZnO matrix for different cobalt contents. The effect of cobalt on these distinct parameters can be exploited for the bio-sensing and optoelectronic device engineering due to its biocompatibility, electron mobility and high surface to volume ratio..


ZnO, Nano structure, Refractive index, Bond length, Resistivity, Biosensors.

Submitted at: Sept. 13, 2016
Accepted at: April 5, 2018


A. ZIA, S. AHMED, N. A. SHAH, Investigation of the sensing mechanism in cobalt doped ZnO matrix based on structural, morphology, optical and electrical studies, Journal of Optoelectronics and Advanced Materials Vol. 20, Iss. 3-4, pp. 180-187 (2018)