Optical, structural, electrical, and morphological properties of (Ga:B) co-doped CdS thin films

Gallium and Boron co-doped Cadmium Sulfides (CdS) films were prepared using the sol-gel technique. CdS and CdS/Ga:B with various concentration films were prepared on a glass substrate by immersing it in the proper aqueous solutions for 2 h and annealing at 450 degrees C for 2 h. The transmittance spectra acquired a blue-shifting by adding Ga and/or B. Adding only gallium reveals the most blue-shifting, indicating an increase in the film's band edge. Moreover, other optical properties were investigated in detail, such as extinction coefficient k, Index of refraction n, and bandgap energy (Eg). The bandgap energy (Eg) has been investigated via the Tauc model. Eg for the un-doped CdS is around 2.36 eV, while it increases by introducing Ga and/or B for all other samples except for CdS/Ga:B (0.25:0.75)%. The X-ray spectra show a hexagonal structure for all films. The crystalline size for the un-doped CdS thin film is 11.19 nm. However, it decreases with CdS/Ga 1% and CdS/B 1% to be 8.23 nm 7.79 nm, respectively. However, other structural properties were investigated in detail, such as Microstrain epsilon, Dislocation density delta, and Crystallite density N. The average electrical conductivity of CdS is 5.61 mu S/cm, which decreases by adding Ga and/or B, reaching a minimum value (0.81 mu S/cm) for CdS/Ga:B (0.50:0.50)%. SEM image for un-doped CdS film was demonstrated accumulated individual crystals with an average size between 80 and 120 nm in isolated islands.