Effect of residual stress on the optical properties of CsCl thin films

Large band gap alkali halides are known to have interesting optical properties. Though expected to be transparent in nature, defects in the crystal structure results in alkali halides having colors. The defects gives rise to new energy levels in the band structure, called color centers. Defects are easily generated on film fabrication and hence study of alkali halides promise to be interesting. In this manuscript we report the optical properties of cesium chloride (CsCl) thin films. We have correlated the optical properties of the films with the lattice size of the polycrystalline films, thus highlighting the strong relationship between the structure and optical properties of alkali halide films.