Akademik Veri Yönetim Sistemi
Tezin Türü: Doktora
Tezin Yürütüldüğü Kurum: İstanbul Üniversitesi, Fen Bilimleri Enstitüsü, Fen Fakültesi Bölümü, Türkiye
Tezin Onay Tarihi: 2021
Tezin Dili: İngilizce
Öğrenci: ADAL .AB.MA.RAJHI
Asıl Danışman (Eş Danışmanlı Tezler İçin): Ayşe Erol
Özet:
In this thesis, electronic charge transport properties of n-type modulation doped (In0.32Ga0.68As/GaAs) quantum well (QW) structures (quasi-2D structures) and single-layer graphene on TiO2/Si substrate (real-2D) structures were studied. The effects of thermal annealing and growth temperature on electronic transport properties of the quasi-2D structures are also studied. In the first part of study, the electrical properties of InGaAs/GaAs quasi -2D samples such as Hall mobility and carrier concentration have been determined using Hall effect measurement at temperatures between 4.2K and 300K. The effect of thermal annealing and growth temperature on electronic transport properties have been investigated and compared in terms of carrier mobility, carried density, effective mass, alloy potential and interface roughness parameters. To determine the dominant scattering mechanisms in the quasi-2D structures (In0.32 Ga0.68As /GaAs), temperature dependent Hall mobility results have been analysed using an analytical model, considering all possible scattering mechanisms in the quasi 2D samples. The magnetotransport measurements was carried out between 4.2K and 300K. The effective mass, Fermi level and 2D carrier density have been calculated by analysing temperature dependence of the amplitude of Shubnikov de Haas (SdH) oscillations. In the second part of study, the electrical properties of a single-layer graphene grown by Chemical Vapour Deposition (CVD) on TiO2/Si substrate (SLG/TiO2 /Si), such as Hall mobility and carrier concentration have been determined by Hall effect measurement at temperatures between 77K and 300K. For explaining the temperature dependence of the carrier mobility. Analytical expressions that given in Section 1.4.2. were used. Longitudinal acoustic phonon scattering, remote interface optical phonon scattering and temperature independent scattering mechanisms were used in the calculations. All quasi-2D samples In GaAs were grown by Molecular Beam Epitaxy (MBE) at Optoelectronic Research Centre (ORC) of Tampere Technique University, Finland. Graphene sample (SLG / TiO2 / Si) were grown and fabricated at İhsan Doğramacı-Bilkent University. The fabrication of quasi-2D materials using photolithography was made at Advanced Lithographic Techniques Laboratory and magnetotransport measurements were carried out Nano and Optoelectronics Research Laboratory and High Magnetic Field Low Temperature Laboratory of Department of Physics, Science Faculty, Istanbul University.