Now showing items 1-20 of 149

    • Atomic theory of the scanning tunneling microscope 

      Tekman, Ahmet Erkan (Bilkent University, 1988)
      The Scanning Tunneling Microscope is proven to be one of the most powerful tools for surface structure determination. Present theories are able to explain the operation of the microscope when the tip is far from the ...
    • Electronic structure of Si/Ge semiconductor superlattices 

      Gülseren, Oğuz (Bilkent University, 1988)
      A brief review about the two dimensional electron systems and especially band offsets is given. The electronic properties of the Si„/Ge„(001) strained superlattices as a function of the superlattice periodicity and the ...
    • High Tc superconductivity 

      Gedik, M Zafer (Bilkent University, 1989)
      critical summary of the recent developments in high temperature superconductivity is given. Physical properties of the new materials are summarized. The new theories proposed to explain high Tc are reviewed. In the case ...
    • Construction of a scanning tunneling microscope and first results 

      Oral, Ahmet (Bilkent University, 1990)
      In this thesis, construction of a Scanning Tunneling Microscope in air is explained. A step motor sample approach mechanism and a tripod scanner are used in the construction. Atomic resolution images of graphite samples ...
    • Phase transitions in tetrahedral Ising lattices 

      Kabakçıoğlu, Alkan (Bilkent University, 1993)
      After a review of the Renormalization CJroup theory, the phase diagram of unisotro])ic tetrahedral Ising lattice is explored l)y the motivation gained through the recent experimental findings about SiGe alloys. ...
    • Controlled lateral and perpendicular motion of atoms on metal surfaces 

      Buldum, Alper (Bilkent University, 1994)
      Nanoscale modification of matter has been the subject of interest. Recently, several experimental studies have demonstrated that by using a scanning tunneling microscope one can translate atoms on metal surfaces to a ...
    • Ridge waveguide GaAS 

      Türkoğlu, Abdullah Kamuran (Bilkent University, 1994)
      The study of solid-state laser structures in low dimensions has gained great deal of attention in recent years. The theory originated in early 1960s developed really fast along with new fabrication methods bringing ...
    • Al(x)Ga(1-x)As/GaAs graded index separate confinement heterostructure single quantum well lasers 

      Bozkurt, Mümtaz Koray (Bilkent University, 1994)
      "Stimulated emission of photons could be produced in semiconductors by recombination of carriers injected across a p-n junction This idea was first suggested by Basov et al} in 1961. Soon afterwards diode lasers were ...
    • Fabrication, characterization, and extraction of GaAs mesfets 

      Ata, Erhan Polatkan (Bilkent University, 1994)
      Metal Semiconductor Field Effect Transistor (MESFET) is the most widely used active element of today’s microwave industry. After development of the MESFET technology, the microwave industry gained a high acceleration, ...
    • Hard spin mean field theory of 3D stacked-triangular-lattice system 

      Akgüç, Gürsoy Bozkurt (Bilkent University, 1994)
      Closed form solution of ‘Hard spin mean field theory’ is constructed and applied to ‘Three dimensional stacked-triangular-system’. The phase diagram of this system is examined. ‘Free energy’ is calculated to reveal ...
    • Phonon renormalization effects in low dimensional electron-hole systems 

      Güven, Kaan (Bilkent University, 1995)
      Ia)vv (linuMisioiial sciniromluclor st i iid iii4's lia\4‘ 1и‘(М1 an (‘Xt(Misiv(‘ i4\soa,rrh iwcix ill (4)iul(4iscd iiiatlcr physics. In j^aii iculai', iiindi (‘llorl has 1)(Ч'п dcvolnd to lhc‘ study ol ciuasi-one-diiiK'iisional ...
    • Supercurrents and persistent currents in strongly correlated electron systems 

      Boyacı, Hüseyin (Bilkent University, 1995)
      The lull understanding· ol’the solution Гог the 1-tl Hubbard model is of interest in its own right, and may provide clues to the understanding of higher dimensioned systiMiis. We have found tin? exact solution of tlie ...
    • Time dependent study of quantum bistabiliity 

      Ecemiş, Mustafa Ihsan (Bilkent University, 1995)
      The analysis of quantum transport phenomena in small systems is a prominent topic of condensed matter physics due to its numerous technological applications. The current analytical theories are not adequate for ...
    • Rabi oscillations in an exciton-polariton system 

      Müstecaplıoğlu, Özgür Esat (Bilkent University, 1995)
      The pure qiiaiitum model d(\scril)ing lîahi oscillations of exciton-polaritons in a ınicro-cavity is consid(‘r(‘(l. IMiolon-c'Xcilon intiT’action Hamiltonian is diagonalized with the aid of Bogoliihov canonical transformations ...
    • Characterization of photonic crystals at microwave frequencies 

      Temelkuran, Burak (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 ...
    • Gain measurements via spontaneous emission in quantum well semiconductor lasers 

      Azfar, Talal (Bilkent University, 1996)
      111 this work ail analysis of gain in single c|iianliini well last'rs as a riinction of sonu' of llu'ir o|)(M’alioiial paranu'l('rs is earrii'd oiil. I^'irsl, a 1 li('or('liea.l inodi'l of gain is |)resent('d. 'riuMi two ...
    • Atomic scale investigation of clean and epi-grown Si(001) surfaces using scanning tunneling microscopy 

      Özer, H Özgür (Bilkent University, 1996)
      III ( liis lİK'.sis, cl('aii and <‘|)i-grovvn Si(üü 1 )(2 x I) suriacc's ai(' aııalysc'd by Scanning 'I'nnnc'ling Micioscopy (S'l'M). 'I'lu' S'l'lM and IMlra High Vacuum SysicMii (UH V) in which thc' microscope is ...
    • Fabrication and characterization of high speed resonant cavity enhanced Schottky photodiodes 

      Islam, M Saiful (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 ...
    • Electronic and atomic processes in nanowires 

      Mehrez, Hatem (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 

      Türeci, E Hakan (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 ...