Effect of substrate temperature on bismuth oxide thin films grown by pulsed laser deposition

We present and discuss on bismuth oxide films grown on cost-efficient BK7 glass slides by pulsed laser deposition using a metallic target. Our choice is of particular interest due to the high number of intermediate bismuth oxides that can form during the oxidation process, along with the polymorphs of the stoichiometric oxide, i.e. bismuth trioxide (Bi2O3). We show that the oxidation degree of bismuth increases with substrate temperature, tS (300-600 °C), when grown in 100 sccm flow at 6 × 10−1 mbar O2 partial pressure. Thin film crystallinity is also increased with tS, as expected. Instead, the refractive index (n) of the films decreases in the visible range, as tS is increased. Furthermore, the transmittance of the films increases with tS to over 60%, especially in the red and near-infrared region (above 600 nm). As a final point, the results are discussed and compared to literature.