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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The Growth Mechanism of Inclined AlN Films and Fabrication of Dual Mode Solidly Mounted Resonators

Chen, Cheng-ting 02 August 2010 (has links)
The 1/4£f dual-mode resonators made from c-axis-oriented aluminum nitride films grown on different conduction material have been studied in this thesis. The RF/DC sputter system is used to grow on layers of reflector. During the porcess, 3.5 pairs of Bragg reflector alternating with W and SiO2 are composed by Si substractor. To achieve 0.999 reflective rate, fabrication parameters are adjusted to make W films become £\-phase structurre. On the other hand, piezoelectric layers as well as reflective layers that using reactive RF magnetron sputtering system and means of off-axis are combined to deposite optimal resonators of shear mode quality factor (Q) resonatros. While changing the substract and target distance between various bottom electrode materials, including Si, W/Si, and Mo/Si could deposit AlN with various c-axis tilting angle which resulted in stimulating longitudinal and shear acoustic waves. Futhermore, the finding is used to discuss the growth mechanism of inclined AlN by TEM. The analysis of various distances of AlN films shows that column inclining angle and XRD-Rocking Curve £s will increase with distance. The quality of shear mode would be better when column and £s are highly shifed. About the influence on AlN deposites, AlN/Si was grown away from the center by 6 cm. AlN/Si column inclining angle is about 20 degree, and RMS could reach 2.63nm beneath. Uner AlN/W/Si, column incling angle is about 30 degree, and £s shift angle 4.14 degree, the shear mode quality factor of freaquency response is obtained to 262. Under AlN/Mo/W/Si, column incling angle would be 25.4 degree, and XRD are better-choosed c-aixsm, £s tilting angle shifs 6.72 degree, and the shear mode quality factor is obtained to 290. Film intersurface appears bigger misfit by TEM to obtain better shear mode.
2

Experiments and finite element simulations of planetary three-roll rolling

Tang, Yi-Chun 28 August 2002 (has links)
This paper is divided into two parts, experiments and finite element simulations. In experiments, the effects of various rolling conditions such as roll rotational speed, reduction, upon entrance and exit axial velocities, entrance and exit rotational speeds, twisting angle of rolled products are investigated. Experiments with roll rotation and planetary rotation are carried out to check the validity of the results obtained by roll rotation only. In finite element simulations, DEFORM 3D is used to simulate planetary three-roll rolling. The rolling torque, the distance between spirals, and the shape are analyzed, and the analytical results are compared with experimental results.

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