  A comparative study of the physical properties of undoped Zinc Oxide (ZnO)
and Al doped Zinc Oxide (AZO) thin films were performed as a function of
annealing temperature. The structural properties were analyzed using X-ray
diffraction and the recorded patterns indicated that the crystallinity of the
films always enhanced with increasing annealing temperature while it degrades
with Al doping. The topographical modification of the films due to heat
treatment was examined by atomic force microscopy which revealed that annealing
roughened the surface of all the films; however the AZO films always exhibited
smoother morphology than ZnO. Study of the optical properties by UV-Visible
spectrophotometer demonstrated that the transmittance was gradually diminished
with the rise in annealing temperature. In addition, a notable increase in the
optical band gap was also observed for the AZO films.
