Browsing Theses - Department of Physics by Issue Date
Now showing items 21-40 of 239
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Electronic and atomic processes in nanowires
(Bilkent University, 1996)The variation of conductance of a nanowire which is pulled between two metal electrodes has been the subject of dispute. Recent experimental set-ups using a combination of STM and AFM show that changes in conductivity ... -
Phonon anomalies in high temperature superconductors
(Bilkent University, 1996)Anomalously large low temperature phonon anharmonicities can lead to static as well as dynamical changes in the low temperature properties of the vibrational system. In this work, we focus our attention on the low ... -
Approximation methods in the polaron theory: applications to low dimensionally confined polarons
(Bilkent University, 1996)The pelaron problem has been of interest in condensed matter physics cind held theory tor cibout half a century. Within the framework of Vcist variety of theoreticcil approximations, the bulk polaron properties have been ... -
Characterization of photonic crystals at microwave frequencies
(Bilkent University, 1996)VVe investigated the surface reflection properties of layer-by-layer photonic crystals, for dielectric and metallic based photonic crystals. By using a FabryPerot cavity analogy with the reflection-phase information of ... -
Fabrication and characterization of high speed resonant cavity enhanced Schottky photodiodes
(Bilkent University, 1996)High speed, high external quantum efficiency and narrow spectral linewidth make resonant cavity enhanced (RC E) Schottky photodetector a good candidate for telecommunication applications. In this thesis, we present our ... -
Impurity effects and symmetry of the order parameter in high-temperature oxide superconductors
(Bilkent University, 1997)Identification of the symmetry of the order parameter (OP) of high-l'c cuprates is important because it helps to understand possible mechanism that govern the physics of these materials. However, up to now, there is no ... -
A time-dependent study of bistability in resonant tunneling structures
(Bilkent University, 1997)A comjDutational time-dependent study of the bistability in resonant tunneling structures including the electron-electron interactions is presented. A new computational method for the investigation of many jDarticle ... -
Hot electron interactions in nanostructures
(Bilkent University, 1997)Modern semiconductor growth and processing techiques have provided the capability of fabricating a huge variety of devices which have atomically precise layered structures and lateral patterns with nanometer sizes. This ... -
Ground-state properties of double-wire semiconducting systems
(Bilkent University, 1997)With the recent advances in nanometer-scale semiconductor device fabrication technology, it became experimentally possible to produce strongly confined electron systems. Quantum wires are among these systems, and are ... -
Atomic, electronic, and transport properties of quantum point contacts on graphite surface
(Bilkent University, 1997) -
GaAs/AlGaAs polarization splitting directional couplers
(Bilkent University, 1997)Directional couplers are building blocks for m any guided wave devices in integrated optics and optoelectronics. They have been used as switches, modulators, wavelength filters, power dividers, wavelength m ultiplexer-dem ... -
Fabrication and characterization of semiconductor double quantum well diode lasers
(Bilkent University, 1998)In this thesis, semiconductor double quantum well, Fabry-Perot and half ring hisers were fabricated, and these devices were operated and characterized at room temperature. The lasers were fabricated using GaAs/AlGaAs ... -
Theory of atomic scale friction
(Bilkent University, 1998)Friction is an old and important but at the same time very complex physical event. This thesis aims to develop an atomic scale theory of friction. VVe investigate various atomic processes and stick-slip motion by using ... -
Fabrication and characterization of high-speed, high quantum efficiency, resonant cavity enhanced Schottky photodiodes
(Bilkent University, 1998)Rapidly developing “photonics” technology promises higher bcindwidths of communiccition than any other techniciue did ever. The increasing rate of communication not only alters science and technology, but brings a global ... -
Low loss optical waveguides and polarization splitters with oxidized AlxGa1-xAs layers
(Bilkent University, 1998)Low propagation loss waveguides, operating at 1.55 fim optical wavelength, are fabricated utilizing oxidized AhGai_a;As layers. MBE grown multilayer semiconductor heterostructures are characterized before and after ... -
Strongly correlated models of high-temperature superconductivity
(Bilkent University, 1999)Son zamanlarda nanometrc büyüklüğündeki örneklerle ya|)dan tek ek'ktron ta.^ınma deneyleri, üstün iletkenlerin büyüklüklerinin alt sının ile ilgili soruyu yeniden gündeme getirmiştir, iler ne kadar, belirsiz tanecik ... -
Long wavelength GaAs based hot electron photoemission detectors
(Bilkent University, 1999)The increasing rate of telecommunication alters both science and technology, and demands high performance components. Photo detectors are essential components of optoelectronic integrated circuits and fiber optic ... -
Many-body interaction effects in quasi-one-dimensional photo-excited electron-hole systems
(Bilkent University, 1999)The work in this thesis concerns rnany-body interaction effects in a quasi-onedimensional electron-hole plasma, which may be generated under intense photoexcitation in a semiconductor quantum-well wire. In particular, ... -
Quantum statistics of light interacting with matter
(Bilkent University, 1999)Studies on some systems in which light interacts with matter are performed from quantum statistical point of view. As a result of these studies a novel effect which can be utilized for detecting squeezed phonons is ... -
Low-temperature thermodynamics of finite and discrete quartic quantum oscillator in one dimension
(Bilkent University, 1999)I.' this work we examined a quartic Hamiltonian using two different approaches. We first introduced a mean-field Gaussian approximation in order to handle this Hamiltonian analytically and observed that this approximation is ...
