Engineering and Technology Journal

Abstract

Structural and optical properties were studied as a function of films thickness for
thermally evaporation PbI2 films. X-ray diffraction analysis confirmed that PbI2
films are polycrystalline having hexagonal structure. The optical absorption data
indicate an allowed direct transmission with optical energy gap varies continuously
from ( 2.15eV to 2.33eV) . The energy gap shows thickness dependence, which
can be explained qualitatively by a thickness dependence of grain size through the
decrease of the grain boundary barrier height with grain size. The low fluctuation
in energy gap indicates that the grain size is quite small, which is finding in
agreement with AFM results.