INVESTIGATION ON LaF_3 MATERIAL IN A SIMPLE STRUCTURE OF Si/LaF_3 AS A POSSIBLE LIGHT-ADDRESSABLE POTENTIOMETRIC FLUORIDE (F~-) SENSOR

摘要

In this article LaF_3 films have been epitaxially grown on 300μm-Si by vacuum evaporation. Structures with various thickness of LaF_3 (5/50/150nm) layer have been studied. The effect of annealing on the structure has also been studied. The sensors are annealed at 400℃ for 10 minutes. The sensors-without-annealing hardly show fluoride sensitivity. The fluoride sensitivity varies with the LaF_3 thickness. Among the annealed sensors, the one prepared with 150nm LaF_3 layer showed the best fluoride sensitivity of ≈ 54.5mV/pF in the range of pF1-pF7. Experimental results show a good promise for Si/LaF_3 structure as a light-addressable potentiometric sensor that can be used for the sensing and imaging the distribution of fluoride ion in aqueous medium.