The formation of the nanocrystals (NCs) by using the sol-gel spin-coating method at various annealing temperatures had been studied. The film started to form the islands at 600 °C annealing, and finally transferred into NCs at 900 °C. A model was proposed to explain the transformation of thin film. The morphology of sol-gel thin film at 600 °C annealing was varied and had higher interfacial energy. The crystallized process at 900 °C annealing could minimize the energy. The retention for 900 °C annealed sample exhibited less than 30% charge loss after 106 s at 125 °C measurement.