The impact of annealing on the dielectric performance of TiO 2 thin films synthesized by PECVD was investigated. Films annealed between 500 and 700 • C have an anatase crystal structure, while 800 • C annealed films display the rutile phase. The optimal annealing temperature was 600 • C, which both maximized the dielectric constant and minimized the leakage current density. The intrinsic dielectric constant of TiO 2 improved from 82 ± 10 in as-deposited films to 168 ± 30 after annealing. The leakage current of optimized films was superior to the SiO 2 control samples over a range of equivalent oxide thickness. Fowler-Nordheim tunnelling and Frenkel-Poole conduction were observed in the optimized films, while Schottky emission dominated leakage current at other conditions.
Self-adaptive applications address environmental dynamics systematically. They can be faulty and exhibit runtime errors when environmental dynamics are not considered adequately. It becomes more severe when uncertainty exists in their sensing and adaptation to environments. Existing work verifies self-adaptive applications, but does not explicitly consider environmental constraints or uncertainty. This gives rise to inaccurate verification results. In this paper, we address this problem by proposing a novel approach to verifying self-adaptive applications suffering uncertainty in their environmental interactions. It builds Interactive State Machine (ISM) models for such applications and verifies them with explicit consideration of environmental constraints and uncertainty. It then refines verification results by prioritizing counterexamples according to their probabilities. We experimentally evaluated our approach with real-life self-adaptive applications, and the experimental results confirmed its effectiveness. Our approach reported 200-660% more counterexamples than not considering uncertainty, and eliminated all false counterexamples caused by ignoring environmental constraints.
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