Systematic study of Ni, Cu co-doped ZnO nanoparticles for UV photodetector application

Abstract

ZnO nanoparticles co-doped simultaneously with Ni and Cu at concentrations varying between 0 and 10% were synthesized by wet chemical method. The resulting nanoparticles were less than ~ 60 nm. At 5% Ni + 5% Cu co-doping, enhanced visible luminescence between 380 nm – 460 nm is seen. Coupled with a low bandgap of 3.4 eV, they result in conducive optical properties for application of this material as UV Photodetector. Marginal changes in bond length (~ 0.003 A) and c/a ratio (~ 0.002 A), along with absence of impurity phases reflect its microstructural superiority. Morphological studies indicate marginal reduction of interplanar spacing due to doping, thus, forming uniform crystalline nanoparticles. The nominal composition of Zn, O, Ni and Cu without any impurity phases remains intact. An overall blue shift in absorption peak for all samples than bulk ZnO is observed, emerging due to size effects. However, at doping concentrations higher than 5%, Cu (111) and Ni (200) phases are seen due to clustering. Electrical studies under UV exposure are in agreement with the characterization studies on the sample, showing highest responsivity, current gain and high quantum efficiency values of 10.003 mA, 1.0421 and 3.146% respectively. These properties enable 5% Ni + 5% Cu co-doped ZnO nanoparticles to be explored for use as a material for optoelectronic devices like UV Photodetector.