Structural and optical properties of Nd3+ doped zinc oxide thin films deposited by spray pyrolysis

Un-doped and Neodymium (Nd)-doped zinc oxide (ZnO) thin films were deposited on glass substrates by spray pyrolysis experimental setup at 400 °C. The doping concentration of Nd is varied between 0.05 at.% and 0.25 at.%, in the spray solution. XRD studies confirmed the hexagonal wurtzite crystal structure of the deposited films irrespective of the variation in the Nd doping concentration. The SEM microstructures reveal that the average diameter of the Nd ring on the ZnO surface is ranging between 1.87 μm and 11.45 μm depending on the Nd doping concentration. EDS analysis confirmed the presence of Nd in the doped samples. Further, it is understood that Nd/Zn ratio in the deposited films is varied between 0.05 at.% and 0.25 at.%. The optical band gap is found to be ranging between 3.20 eV and 3.22 eV for the variation in Nd/Zn ratio from 0.05 at.% to 0.25 at.%. The PL of films is more intensive in UV region. Concentration of oxygen vacancy related defects and excitation wavelength in ZnO film were observed by PL studies. The green emission has been interpreted as the transition between singly charged oxygen vacancy and a photoexcited hole from PL studies.