Highly oriented and conducting Bi doped ZnO (BZO) layers chemically sprayed using nitrogen gas carrier

In this work, we have successfully prepared the highly conducting and transparent Bi doped ZnO (BZO) thin films using pneumatic spray pyrolysis technique with nitrogen (N2) carrier gas. The evolutions of structural, morphological and opto-electrical properties of the BZO films as a function of Bi concentration were analyzed. It is found that the films are uniform with no haze or visible clusters. X-ray diffraction shows that all the films were polycrystalline with hexagonal wurtzite structure, without secondary phases. All the BZO layers exhibit the classical preferential orientation of (002) plane and it changes in favor of (100) plane at 3 wt% Bi. The BZO thin films showed 83% as a value of average optical transmittance in the visible region. The optical band gap values oscillated around 3.23 and 3.27 eV. The SEM micrographs show clusters and nano-crystalline grains with special shape on the surface. The photoluminescence spectra of the films exhibits ultraviolet and green emissions. The electrical resistivity reaches a minimum value (8.4310−3 Ωcm) at 1 wt% Bi.