The thermally evaporated stoichiometric CdI2 films show good c-axis alignme
nt normal to substrate plane for film thickness up to 200 nm, The optical a
bsorption data indicate an allowed direct interband transition across a gap
of 3(.)6 eV in confirmation with earlier band structure calculations, Howe
ver, part of the absorption data near band edge can be fitted to an indirec
t band gap of 3 eV. The dependence of band gap on film thickness (> 200 nm)
can be explained qualitatively in terms of decreasing grain boundary barri
er height with grain size.