Nanostructured Gd_xZn_(1-x)O thin films by nebulizer spray pyrolysis technique: Role of doping concentration on the structural and optical properties

摘要

Nanostructured Gd_xZn_(1-x)O thin films with different Gd concentration from 0% to 10% deposited at 400 ℃ using the NSP technique. The films were characterized by structural, surface and optical properties, respectively. X-ray diffraction analysis shows that the Gd doped ZnO films have lattice parameters a = 3.2497 A and c = 5.2018 A with hexagonal structure and preferential orientation along (002) plane. The estimated values compare well with the standard values. When film thickness increases from 222 to 240 nm a high visible region transmittance (>70%) is observed. The optical band gap energy, optical constants (n and k), complex dielectric constants (ε_r and ε_i) and optical conductivities (σ_r and σ_i) were calculated from optical transmittance data. The optical band gap energy is 3.2 eV for pure ZnO film and 3.6 eV for Gd_(0.1)Zn_(0.9-) O film. The PL studies confirm the presence of a strong UV emission peak at 399 nm. Besides, the UV emission of ZnO films decreases with the increase of Gd doping concentration correspondingly the ultra-violet emission is replaced by blue and green emissions.