Doping Efficiency in Cobalt-Doped ZnO Nanostructured Materials

Abstract

Nanostructured ZnO thin films doped with cobalt from 5% to 20% were grown on glass substrates by a low-temperature chemical bath deposition (CBD) technique. We compared the doping efficiency of incorporating cobalt in ZnO nanostructured samples doped with cobalt via cobalt nitrate and cobalt chloride. The concentration of cobalt incorporated into the ZnO matrix was precisely determined using inductively coupled plasma mass spectroscopy (ICP-MS). Scanning electron microscopy (SEM) images showed that only at a 0.1 M ratio of the precursor solutions in CBD using cobalt nitrate as a dopant, the morphology of ZnO yielded hexagonally shaped nanorods. At a 1 M ratio of the precursor solutions, SEM images showed that the morphology of ZnO was nanoplatelets at all doping levels, irrespective of the doping method used. The synthesized nanostructures retained the wurtzite hexagonal structure only at 0.1 M precursor solution using cobalt nitrate doping, which was confirmed by X-ray diffraction (XRD) studies. In cobalt-doped samples using cobalt chloride as a dopant, XRD analysis confirmed the formation of a Simonkolleite structure. At 300°C, the Simonkolleite structure was converted to a wurtzite structure without changing the morphology. Electrical conductivity measurements at 300 K showed that ZnO nanorods doped with cobalt using cobalt nitrate yielded the lowest resistivity. The molarity of the precursor solution and dopant was found to have a substantial impact on the morphology and doping efficiency of the ZnO nanostructures.

Enhancement in the performance of nanostructured CuO–ZnO solar cells by band alignment

“…The detailed process of fabricating ZnO and cobalt doped ZnO nanorods using chemical bath deposition (CBD) was discussed in detail in our previous studies. [35][36][37][38][39][40][41] For CuO nanostructures, the growth mechanism was a modied chemical bath deposition (CBD) method in which equimolar 0.1 M of copper nitrate trihydrate (Cu(NO) 3 $3H 2 O) and hexamethylenetetramine (C 6 H 12 N 4 ) was dissolved in deionized water under constant stirring. Few drops of ammonium hydroxide solution (30-33% NH 3 in H 2 O) was added to the resulting precursor solution until the pH reached 8.…”

Structural and magnetic properties of cobalt doped ZnO thin films deposited by cost effective nebulizer spray pyrolysis technique

“…The grain size reduced with increase of cobalt doping concentration whereas it forms densely packed network. It is clearly observed that for increase in cobalt concentration from 1% to 7% the grain size was found to be decreased [33,34] according to the figures 3(d), (e). Here it was noticed that the dopant deteriorate the degree of crystallization through its substitution.…”

Sensitivity of Nanostructured Mn-Doped Cobalt Oxide Films for Gas Sensor Application

“…An aqueous solution of 0.1 M of CoCl 2 .6H 2 O supplied from Merck Chemicals (Germany) was used to prepare thin films of Co 3 O 4 [25], and 0.1 M of Manganese chloride MnCl 2 •4H 2 O was used as doping agent with a concentration of 1% and 3% to obtain Mn doped cobalt chloride [26]. A few drops of HCl were added to obtain a homogeneous solution.…”