ADCs of lung carcinomas overlap, but ADCs of well-differentiated adenocarcinoma appear to be higher than those of other histologic lung carcinoma types.
Microstructure dependence of electrical properties of (Ba0.5Sr0.5)TiO3 thin films deposited on Pt/SiO2/Si Preparation of thinfilm (Ba0.5,Sr0.5)TiO3 by the laser ablation technique and electrical properties
Pb(Zr, Ti)O3 thin films of thickness ranging from 55 nm to 625 nm were synthesized on Pt/Ti/SiO2/Si substrates using a sol-gel process. The film thickness dependence of both microstructure and electrical properties was investigated. The synthesized films showed columnar structure. The diameter of each column was around 100 nm regardless of the film thickness. The 328 nm-thick film exhibited a dielectric constant (ε) of 1000, remanent polarization (P
r) of 20 µC/cm2, and coercive field (E
c) of 47 kV/cm. Both ε and P
r decreased and E
c increased with decreasing film thickness. This behavior is attributed to the existence of a low-dielectric-constant interface layer. The results of leakage current measurement were in good agreement with the model of space-charge-limited current.
RuO2 thin films have been prepared onto sapphire by reactive sputtering with Ar+O2 plasma and their application as the bottom electrode in the high dielectric constant (Ba0.5Sr0.5)TiO3 (BST) thin film capacitor has been studied. RuO2 films with rutile structure are obtained with O2 content greater than 0.7. The dielectric constants of the sputtered (Ba0.5Sr0.5)TiO3 films on the RuO2 films are 250 for 49-nm-thick film and 460 for 130-nm-thick film. These values are comparable with those on Pt and Pd, which are commonly used as the bottom electrodes. No remarkable interdiffusion at the BST/RuO2 interface region and no hillocks at the RuO2 surface were observed, even after BST film deposition at 620 °C. RuO2 is one of the promising materials for use as the bottom electrode for the (Ba0.5Sr0.5)TiO3 thin film capacitor.
High dielectric constant SrTiO3 thin films were sputter deposited on barrier layers/Si substrate to fabricate a capacitor for dynamic random access memories. Dielectric constant (εr) values of 140–210 were achieved for the 150-nm-thick SrTiO3 films using a Pt/Ti or Pt/Ta double-layer barrier. In the Pt(50 nm)/Ti(10 nm), Pt(50 nm)/Ti(50 nm), and Pt(50 nm)/Ta(10 nm) barrier, effective εr decreased by annealing in the temperature range between 450 and 550 °C, where the interdiffusion of Pt and Si was confirmed by x-ray diffraction analysis and cross-sectional transmission electron microscopy. In the Pt(50 nm)/Ta barrier, increase of the Ta thickness from 10 to 50 nm brought out a remarkable improvement of endurance to high-temperature annealing. That is, in the Pt(50 nm)/Ta(50 nm) barrier, large εr value (∼200) was maintained even with annealing at up to 700 °C.
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