Effects of annealing temperature and Al2O3 buffer layer on ZnO thin films grown by atomic layer deposition

ZnO thin films have been prepared on Al2O3/Si by atomic layer deposition (ALD) at 150 oC process temperature. After deposition, post-growth annealing was carried out on the ZnO thin films under N2 ambient at different annealing temperatures. The Surface morphology and optical property of ZnO/Al2O3/Si were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence (PL). The qualities of annealed samples are improved significantly compared with as-grown ZnO/Al2O3/Si. In particularly, it shows gradual improvement of optical property with increase of annealing temperature. The effect of Al2O3 buffer layer was also investigated comparing ZnO/Al2O3/Si and ZnO/Si annealed at high temperature (⩾800 oC).