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

Abstract

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 (Bi 2 O 3). We show that the oxidation degree of bismuth increases with substrate temperature, t S (300-600 °C), when grown in 100 sccm flow at 6 × 10 −1 mbar O 2 partial pressure. Thin film crystallinity is also increased with t S , as expected. Instead, the refractive index (n) of the films decreases in the visible range, as t S is increased. Furthermore, the transmittance of the films increases with t S 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.

Influences of Substrate Temperatures and Oxygen Partial Pressures on the Crystal Structure, Morphology and Luminescence Properties of Pulsed Laser Deposited Bi2O3:Ho3+ Thin Films

“…These calculations indicated that the direct allowed bandgaps for the Bi2O3:Ho 3+ thin films were 2.89, 2.20, 2.18, 2.33, 2.36 and 2.56 eV for TS of RT, 200, 300, 400, 500 and 600 °C, respectively. These values correspond well with those reported previously [11] and with the 2.85 eV [1] that was reported the optical band gap for a 1 mol.% Bi2O3:Ho 3+ powder. The obtained optical band gap values for TS of 200 to 600 °C are relatively smaller than the previous reported values for the powder sample, and that may have been due to the high density of structural defects and presence of the hetero α-and β-phases present in the current products.…”

“…The obtained optical band gap values for T S of 200 to 600 • C are relatively smaller than the previous reported values for the powder sample, and that may have been due to the high density of structural defects and presence of the hetero αand β-phases present in the current products. interference [11,75]. The results in Figure 20 clearly indicate that the reflectance is dependent on the film thickness, and the highest reflectance was achieved for the films grown at the RT that coincided with the thickest film observed.…”

“…In addition, the small absorption at the 495 nm is assigned to the structural defects [2,74]. Figure 20 shows the diffused reflectance spectra oscillated and the lowest reflectance was due to the non-homogeneity of the films and non-uniformity particle distributions, resulting in multiple reflections from the interfaces and to their interference [11,75]. The results in Figure 20 clearly indicate that the reflectance is dependent on the film thickness, and the highest reflectance was achieved for the films grown at the RT that coincided with the thickest film observed.…”

“…Recent articles on the use of PLD for Bi 2 O 3 thin film deposition reported cost-efficient BK7 glass slide deposition with substrate temperatures ranging between 300 and 600 • C and included a report on the crystal structure, morphology and optical properties of the deposited material. Results which indicated the formation of various energy bandgap values for the different films may have useful applications in several optoelectronics industries [11].…”

Observation of the early stages of GaN thermal decomposition at 1200 °C under N 2

“…From spectra in Fig. 2, the film thickness (d) can be calculated in each period by the following equation [25]:…”