| Summary: | 博士 === 國立中央大學 === 化學工程與材料工程研究所 === 99 === In this thesis, we would propose a method which can decouple and estimate the oxygen-vacancy concentration and the cation-substitution concentration in an extrinsic metal oxide thin film separately. Also, we further propose how the properties of the dopant affect the cation-substitution reaction and the oxygen-vacancy concentration by observing the annealing ambient effects. In chapter 3, we propose the method which could estimate the oxygen-vacancy concentration and the cation-substitution concentration by measuring the carrier concentration of the thin film, which is annealed in different oxygen partial pressure. In chapter 4, we would discuss that how the difference of the electronegativity and the electron configuration would govern the cation-substitution reaction and the oxygen-vacancy formation reaction n. And how do oxygen-partial pressure and annealing temperature affect on the oxygen-vacancy concentration and the cation-substitution concentration. We found that the electronegativity would affect the cation-substitution concentration when the thin films were annealed at different oxygen pressure. And the electron configuration would affect the band diagram and affect the oxygen-vacancy formation energy. Besides the basic electrical properties, we also study the optical properties of ITO based thin films.
In chapter 5, we found that the as-deposited ITO/Al structure would absorb particular light (400 nm- 600 nm) after thermal treatment. It is because the Al diffusion in ITO would locate at the interstitial site and serve as a defect level. Yet, we found that the pre-annealed ITO thin film is a good diffusion barrier layer which can retard the Al diffusion. On the other hand, by measuring the transmittance of the M:ITO thin films, we found that the transmittance of the extrinsic metal oxide in the near-UV region could be enhanced by doping the ternary metal. The transmittance of ITO thin film at near-UV region (380 nm) could be enhanced 22 % after doping Ti. Thus, after applying the Ti:ITO thin film on near-UV LED as the current spreading layer, the light output power of the near-UV LED is enhanced 52.1 %.
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