Physics Commons^™

Design And Modeling A Tunable Non-Hermitian Acoustic Filter, Sandeep Puri

Theses and Dissertations

In this thesis, we explore an application of a non-Hermitian acoustic system with tunable loss in filtering specific frequencies from an upcoming signal at will. Using the commercial computational software, we design our proposed tunable filter made of a phononic super-lattice. The super-lattice consists of two sublattices connected in series. The first sublattice is Hermitian, whereas the other can be Hermitian or Non-Hermitian depending on the amount of loss induced in it. By introducing the loss in the system, we observe the generation of absorbed resonances that can be seen in the reflection spectrum. The range of the filtered frequencies …

Theoretical Investigations Of Zinc Blende And Wurtzite Semiconductor Quantum Wells On The Rotated Substrates, Igor Ivashev

Theses and Dissertations (Comprehensive)

We present a comprehensive set of computations of effective mass theory for both the Kane's parabolic band approximation and Luttinger-Kohn's valence band mixing approximation. We generalize the kp method to be able to evaluate band structures for the materials such as zincblende InGaAsN and GaAsBi compounds used in long wavelength lasers and wurtzite materials used in short wavelength lasers. We investigate methodology to study band structure of semiconductors that are grown away from natural direction. The strain influence is introduced via Bir and Pikus model. It is expected that band structure is strongly dependent on direction of crystal growth and …

Mechanical, Electronic And Optical Properties Of Multi-Ternary Semiconductor Alloys, Dongguo Chen

Dissertations

The ability to obtain tunable properties with composition makes multi-ternary alloys extremely useful for a variety of applications in semiconductor devices and is of significant interest in experimental and theoretical research. This dissertation investigates the mechanical, electronic and optical properties of multi-ternary, i.e., binary, ternary and quaternary, semiconductor alloys using analytical methods and first-principles calculations.

For the calculations of mechanical properties, existing models on the average shear modulus of III-V & II-VI binary semiconductors are revised. New expressions are developed for the average Young’s modulus as well as the shear modulus and Young’s modulus on (111) plane for these compounds. …

Understanding The Origins Of Metastability In Thin Film Growth; Tantalum And The Early Group Vb-Vib Metals, Neme Okechukwu Nnolim

Dissertations

Tantalum (Ta) is a metal that is highly prized for its applications in a variety of industries, including the microelectronics industry, where it is largely used in thin film modifications in order to achieve various electronic, magnetic and structural capabilities in solid-state devices. Ta frequently forms metastable phases, including the well-known ß-phase, during the preparation of thin Ta films by standard film deposition methods such as sputtering and electro-deposition. In order to gain insight into Ta metastable phase formation, the Bain transformation mechanism is studied for Ta and the neighboring body centered cubic (bcc) transition metals in Groups 5 and …