Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Molecular Beam Epitaxial Growth of Znse on (211)b Gaas(Izmir Institute of Technology, 2017) Yavaş, Begüm; Ateş, Serkan; Özçelik, SerdarThe 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 Characterization of Gaas (211) Surface for Epitaxial Buffer Growth(Izmir Institute of Technology, 2014) Polat, Mustafa; Selamet, YusufGaAs (211)B wafer can be used for the growth of CdTe buffer layer by MBE after thermal desorption of oxide presents on its surface. Then, CdTe buffered GaAs (211)B called as composite substrate can be used as a template for the growth of HgCdTe. Thermal desorption can be detrimental to surface in some cases if the structure and constituents of this oxide are not fully understood. In this thesis, HF:H2O and H2SO4:H2O2:H2O chemical treatments were applied to epiready GaAs (211)B samples for the determination of suitability of their usage for CdTe buffer layer growth. Effects of these wet chemical etching processes on the surface of samples are characterized and determined by various kinds of characterization techniques including XRD, XPS, SEM, EDX, AFM, and optical microscope. We also analyzed samples cut from 3" epiready GaAs (211)B wafers to determine their oxide structures, surface roughnesses, crystal qualities, and surface morphologies. Crystal quality of as-received samples measured by RC were about 18-21 arcsec. Amounts of arsenic and gallium oxides were decreased after HF treatment according to XPS results. Gallium rich surface was obtained for samples treated with piranha solution. Surface roughnesses of samples increased after piranha treatment. However, it was determined that others treated with HF had smaller surface roughnesses than asreceived samples.