[en] Sputtered zinc oxide (ZnO) thin films deposited on unheated glass substrate under different sputtering gas mixtures (Ar+O_2) have been investigated using X-ray diffraction and photo luminescence spectroscopy. Earlier reported studies on ZnO films prepared by different techniques exhibit either a sharp/broad near band edge (NBE) emission peak depending on the crystalline quality of the film. In the present study zinc oxide films, grown on unheated substrates, are seen to possess a preferred (002) orientation with a microstructure consisting of clustered nano-sized crystallites. The splitting in the near band edge emission (NBE) into three characteristic peaks is attributed to quantum confinement effect, and is observed specifically under an excitation of 270 nm. Deep level emission (DLE) in the range 400 to 700 nm is not observed indicating absence of deep level radiative defects.

[en] Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O_2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

[en] Highlights: • Co–O–Co bonding influences are observed on Co doped ZnO nanoparticles. • Suppression of Zinc interstitials, Zn_i and oxygen vacancies, V_o is noted with increased doping. • Exceptionally low level of BMP density (3.22 × 10⁷/cm³) is noted in 5 mol% doped nanoparticles. • Enhanced luminescence characteristics justify the nanoparticles suitability for optical devices. Co–O–Co bonding mediated influences are discussed on the structural, defect content, magnetization and luminescence characteristics of Co doped ZnO nanoparticles. X-ray diffraction (XRD) studies indicated an increased fraction of secondary phase while varying Co doping levels from 0.45 to 5 mol%. Contrarily, a reverse trend is noted on the concentration of Zinc interstitials, Zn_i and Oxygen vacancies, V_o defects through Photoluminescence (PL) spectroscopy. For 5 mol% doping level, Bound Magnetic Polaron (BMP) model fitting of Magnetization versus magnetic field, M(H, 300 K) curve yields an exceptionally low level of BMP density i.e., 3.22 × 10⁷/cm³ thereby governing the dominance of Co–O–Co exchange interactions over V_o based Co–V_o–Co interactions; while PL result displays an enhanced UV emission efficiency suitable for short wavelength optical devices.