Intrinsic and dandelion-like microflower nano-rod structures of boron-doped ZnO thin
films were synthesized with an ecofriendly and cost-effective chemical bath deposition technique
from an aqueous solution of zinc nitrate hexahdyrate [Zn(NO3)2.6H2O] as a precursor solution and
boric acid as a doping solution. The boron concentrations were 0.1, 0.3, 0.5, 1.0, 3.0, 5.0, and 7.0
by volume. Scanning electron micrographs showed that doping with boron appears to hinder the
vertical alignment of crystallites. Additionally, independent hexagonal nano-rod structures were
observed to coalesce together to form dandelion-like structures on the film’s surface. The atomic ratio
of the elements was determined via the X-ray photoemission spectrum technique. There were no
substantial changes in the vibration structure of the film upon doping in terms of the Raman spectra.
The optical band gap of ZnO (3.28 eV) decreased with B doping. The band gap of the ZnO:B film
varied between 3.18 and 3.22 eV. The activation energy of the ZnO was calculated as 0.051 eV, whereas
that of the ZnO:B film containing 1.0% B was calculated as 0.013 eV at low temperatures (273–348 K),
versus 0.072 eV and 0.183 eV at high temperatures (348–523 K), respectively. Consequently, it can be
interpreted that the 1% B-doped ZnO, which has the lowest activation energy at both low and high
temperatures, may find some application areas such as in sensors for gases and in solar cells.