Silicon and Silicon-Tellurium films were prepared in an ultrahigh vacuum system. The d.c. electrical conductivity of these films were measured under vacuum before exposing them to the air. The thermal activation energies of Silicon-Tellurium films were always found to be greater than that of Silicon films. Furthermore the optical measurements on Silicon-Tellurium films indicated that the optical gap of these films decreases as the concentration of tellurium in the films increases. Electron microscope examinations revealed that the films were amorphous in structure and homogeneous in composition.

The redox dynamic of electrochemically prepared thin films of polypyrrole is studied. A semi‐empirical formula to explain the redox behavior is formulated and it seems applicable to the reduction dynamic. The redox dynamic is dominated by a diffusion process, depending on the relation between the film thickness and the rise time (t1/2) of the reduction process. The diffusion coefficient, D, was measured to be 2 × 10−9 cm2/sec for perchloride (ClO4−) anion dopant and 1.1 × 10−9 cm2/sec for para‐toluenesulfonate (PTS−) anion dopant. The polypyrrole films exhibited a color change during the oxidation and reduction processes. The electrooptical properties of these films are studied.