Optical and Structural Properties of Ga and in Co-Doped ZnO Nanocrystals Films

The impact of double donor doping on the crystal structure, emission, and electrical resistivity has been studied in the ZnO:Ga:In films. The films were deposited by ultrasonic spray pyrolysis on a previously cleaned silicon substrate. To the study of double donor doping, two groups of samples were prepared. In the first group the In content was 1at% and the Ga contents were varied in the range 0.5-3.0at.%. In the second group the In content was 2at% and the Ga content were changed in the range 0.5-2.5at%. To stimulate the film crystallization, all samples were annealed at 400 o C for 2 hours in nitrogen flow 5l/min. The high quality nanocrystal (NC) films with the wurtzite-type crystal structure, bright near band edge (NBE) emission and the small intensity of defect related PL bands have been obtained. The variation non monotonically of the ZnO crystal lattice parameters, as well as the PL intensities of NBE emission bands has been detected. The reasons for the parameter variation non monotonically and the optimal concentrations for the Ga/In double donor doping of ZnO NC films have been analyzed and discussed.