Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Ateş, SerkanPublisher: search.filters.publisher.Izmir Institute of Technology

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  • Master Thesis
    Molecular Beam Epitaxial Growth of Znse on (211)b Gaas
    (Izmir Institute of Technology, 2017) Yavaş, Begüm; Özçelik, Serdar; Ateş, Serkan; Ateş, Serkan; Özçelik, Serdar; 04.01. Department of Chemistry; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    The Mercury Cadmium Telluride (Hg1-xCdxTe) play important role for infrared (IR) focal plane array application. It is grown on variety alternative substrates which are Si, Ge, GaAs or GaSb. When GaAs is compared with the others alternative substrate, it is more preferable due to having good surface polarity and also easily commercially available of high quality. When HgCdTe epilayer is grown directly on the GaAs substrate, there exist some dislocations in the epilayer due to large lattice mismatch between HgCdTe and GaAs substrate.The CdTe semiconductor is grown like a buffer layer to reduce dislocation in the HgCdTe epilayer grown on GaAs or other alternative substrate [1].The crystal quality of CdTe buffer layer directly affected HgCdTe epilayer. Therefore, CdTe needed to be low defect density.Because of %14.6 lattice mismatch between CdTe and GaAs [2], some defects are observed in CdTe buffer layer. ZnSe epilayer can be used to decrease lattice mismatch between CdTe and alternative substrate. When ZnSe interlayers are grown with high quality, CdTe affects positively. The aim of this theses is the growth of ZnSe epilayer films on (211) GaAs substrates by molecular beam epitaxy (MBE). The effect of growth temperature, VI/II flux ratio and deoxidation process with In and As were studied in this study. Crystal qualities of films were investigated by using X-ray diffraction. The surface morphology of ZnSe films were analyzed by atomic force microscopy and Nomarski microscopy. Vibrational phonon modes, thermal and elastic strains of ZnSe epilayer were observed by using Raman spectroscopy.
  • Master Thesis
    Temperature Dependence of Zero Phonon Line Emission From Defects in Hexagonal Boron Nitride and Design of Photon-Pair Source
    (Izmir Institute of Technology, 2017) Polat, Nahit; Polat, Nahit; Ateş, Serkan; Ateş, Serkan; 04.04. Department of Photonics; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    This thesis presents studies of the defect centers in hBN and design of nonlinear waveguide. The multilayer hBN flakes and Si3N4 waveguide are available materials in modern nanophotonics applications. The color centers in hBN are consisted of quantized states because each defect center has different saturation power and dipole polarization. The line shape of emission from defect centers is directly depended photon vibrations and temperature of sample. Moreover, phonon bands in the color centers affect the wavelength of emission and we statistically worked on the phonon effects on ZPL. The Si3N4 waveguide can be more efficient chip scale photon pair sources to create entangled photons in visible band. The zero dispersion wavelength calculations give an efficient waveguide geometry as 650×600 nm2 for 780 nm pump wavelength.
  • Master Thesis
    Visible Photon Emission From Defects in Hexagonal Boron Nitride Flakes
    (Izmir Institute of Technology, 2017) Fırat, Volkan; Ateş, Serkan; Ateş, Serkan; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Geniş band aralığına sahip kristallerde bulunan renk merkezleri, band aralığı içerisinde kesikli enerji seviyeleri oluşturur. Bir çok kuantum optik ve kuantum bilgi uygulamaları için gerekli olan tek-fotonlar bu kesikli enerji seviyeleri kullanılarak elde edilebilir. Bu çalışmada, çok katmalı hekzagonal bor nitrür (hBN) pulları içinde, tavlama tekniği kullanılarak optik-aktif kusurlar oluşturuldu. Farklı tavlama sıcaklıklarında (500, 750 ve 850°C) yedi örnek ve kıyaslama için iki tavlanmamıs¸ örnek hazırlandı. hBN geniş band aralığı sayesinde görünür bölgede ışıma yapan kusurları barındırabilir. hBN pulları içerisindeki noktasal kusurları bulmak için mikro-fotolüminesans haritalama yapıldı. Daha sonra uyarma gücüne, polarizasyona ve sıcaklığa bağlı ölçümler yapıldı. Ölçümler sonucunda kusurların ortalama 0.5 m boyutlarında olduğu, göreceli olarak düşük uyarma güçlerinde doyuma ulaştıkları, dipole özellik gösterdikleri, 0.8 meV kadar dar genişlikte sıfır-fonon çizgisine sahip oldukları gözlemlendi. Bu sonuçlar kesikli enerji seviyelerine sahip, optik-aktif kusurların oluştuğunu göstermektedir.