Characterization of lattice mismatch indüced dislocations on epitaxial CdTe films için kapak resmi
Characterization of lattice mismatch indüced dislocations on epitaxial CdTe films
Bilgilisoy, Elif, author.
Yazar Ek Girişi:
Fiziksel Tanımlama:
xv, 116 leaves: color illustraltions.+ 1 computer laser optical disc.
Mercury Cadmium Telluride (HgCdTe) is a widely used material for infrared focal plane array applications. In order to produce high quality infrared detecting material, HgCdTe needs to be grown on large area alternative substrates such as GaAs, GaSb, Si or Ge. GaAs is the best choice as an alternative substrate due to its surface polarity and commercially availability of high quality epi-ready wafers. However, there exists a lattice mismatch between HgCdTe and GaAs. To minimize the detrimental effect of the large lattice mismatch between the two materials, Cadmium Telluride (CdTe) is preferred as a buffer layer for HgCdTe IR material. The lattice mismatch between HgCdTe/CdTe and the GaAs substrate results in a large number of misfit dislocations. Dislocation density of the buffer layer limits and reduces the detector device performance. For this reason, the crystal quality and dislocation analysis of CdTe are examined in detail to produce large area and high performance HgCdTe IR devices. The aim of this thesis is the characterization of lattice mismatch induced dislocations on epitaxial CdTe buffer layers. CdTe epilayers which were grown on (211)B GaAs by molecular beam epitaxy (MBE) were subjected to two different etch treatments to quantify the crystal quality and dislocation density. The crystal quality was also obtained by using x-ray diffraction (XRD) measurements. The thicknesses of the samples were measured by ex-situ spectroscopic ellipsometry (SE). The surface morphologies of the CdTe buffer layers were analyzed by atomic force microscopy (AFM), scanning electron microscopy (SEM) and Nomarski microscopy before and after wet chemical etching. Vibrational phonon modes distributions of the as-grown and etched samples were examined by Raman spectroscopy mapping. The “triangle” and “trapezoid” shaped etch pits were compared due to the Everson and Nakagawa etching solutions, respectively. Measured etch pit density (EPD) values of “triangle” etch pits were found in 0.3x108 – 3.8x108 cm-2 range and “trapezoid” shaped etch pits were found in 0.03x108 – 0.6x108 cm-2 range for samples.
Yazar Ek Girişi:
Tek Biçim Eser Adı:
Thesis (Master)--İzmir Institute of Technology: Physics.

İzmir Institute of Technology: Physics--Thesis (Master).
Elektronik Erişim:
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Durumu/İade Tarihi
Tez T001342 QC611.6.M64 B59 2015

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