Structural and optical properties of silicon by tilted angle evaporation

We fabricate the silicon (Si) films on Si substrate by using the tilted angle evaporation technique. The deposition rate of Si films is decreased with increasing the tilted angle of substrate. The refractive index (n) and extinction coefficient can be engineered by the introduction of the porosity into Si films. The refractive index of Si films is controllably varied from 3.4 to 1.6 in the visible wavelength range for different incident angles of Si flux. The extinction coefficient also becomes lower for the larger tilted angle. The porous Si films (i.e., low-n Si) with an inclined nanocolumn structure are observed after evaporation, depending on the incident angle of Si flux. The reflectance of deposited Si films on Si substrate is measured by a spectrophotometer in comparison with theoretical calculations by rigorous coupled-wave analysis and transfer matrix method. These reflectance results are well consistent with the simulated results obtained using the measured refractive index values of the deposited Si films.