Physical characteristics of thermally evaporated Bismuth thin films

Thin films of bismuth with different thicknesses were produced by thermal evaporation from a molybdenum boat source onto cleaned glass substrates at room temperature. The material has been characterized using X-ray diffraction, electrical and optical measurements. A polycrystalline transition phase was observed. The resistivity was calculated for different film thicknesses and found to vary with thickness and temperature. An anomalous dependence of resistivity on temperature was observed during heating. The optical constants were determined from the transmission and reflection data of these thin films for normal incidence. The absorption coefficient revealed the existence of an allowed direct transition with energy gap (Eg) values ranging from 3.45 to 3.6 eV.