Sr-doped ZnO thin film on a silicon substrate (100) grown by sol-gel method: Structural and optical study

In the current study, Sr-doped ZnO thin films were fabricated through a sol-gel route on a silicon substrate (100). The structural, optical, and morphological studies were examined through XRD, UV–vis, PL spectroscopy, and SEM. The crystalline superiority is enhanced through increasing Sr content while the optical bandgap is reduced because of lattice distortion and the production of active imperfections in ZnO, which may be the reason for bandgap tailing. The grain sizes observed are 53, 54, and 60 nm for ZnO, ZnSr1%, and ZnSr2%. Microstructural and strain were explored through Scherrer, W–H, and SSP methods. Furthermore, peak broadening was investigated using these methods. UV–Vis spectroscopy was employed to investigate the band gap of all grown thin films, which are 3.37, 3.28, and 3.20 eV of ZnO, ZnSr1% and ZnSr2%. The optical study was carried out to investigate the band gap, including different parameters such as Absorbance (A), transmittance (T), absorption coefficient ($\alpha )$, band gap (E_g) using different methods, band gap by derivative method, urbach energy (E_u), skin depth (δ), optical density (OD), refractive index (n), extinction coefficient (k), optical conductivity (σ_opt), dielectric constants (ε_r, ε_i), and Tan (α) were also explored. PL spectroscopy was used to study the defects in grown thin films. SEM was employed to examine the morphology of all fabricated thin films. ZnO thin film is widely studied for optoelectronics applications.