Microstructure and related properties of obliquely deposited AgCl thin films

Thin films of crystalline silver chloride are deposited under high vacuum conditions via thermal evaporation of pure AgCl onto pre-cleaned soda-lime glass substrates. A grAlN-like surface structure and columnar growth morphology are visualized by means of a scanning electron microscope. The increase of the vapour incidence angle α is accompanied with a rise in the film porosity and roughening of the sample's surface structure. As a result, the microhardness, DC conductivity and the refractive index of the obliquely deposited AgCl thin films decrease abruptly at α > 50°. The measured efficiency for the detection of humidity or reactive vapours, such as ammonia and dimethylamine, demonstrate that the relative sensitivity of the obliquely deposited AgCl films is several times higher, as compared to the samples obtAlNed at normal vapour incidence.