Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Temperature Dependence of Resistivity and Hall Coefficient in Cu2znsns4 Absorbers for Thin Film Solar Cells(Izmir Institute of Technology, 2017) Akça, Fatime Gülşah; Aygün, Gülnur; Özyüzer, Lütfi; Aygün Özyüzer, Gülnur; Özyüzer, Lütfi; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technologyenergy is the most powerful clean energy source to act on the current energy needing all over the world. The utilization of green energy systems should be promoted since these energy systems benefit consumers, industry and the environment effectively for the developing countries. This advancement can be solely achieved if renewable energy sources become more accessible. It means that not only cheaper but also handy clean energy systems are needed. In spite of relatively high efficiency obtained by using c-Si, Si solar modules require high budget for manufacturing. The high production cost of c-Si, PV industry is lead to search for cheaper candidate materials like Cu2ZnSnS4 (CZTS) as absorber layer in solar cells. The aim of the thesis is to investigate electrical properties of CZTS p-type intrinsic semiconductor compound on soda lime glass substrates, including the temperature dependent electrical conductivity, carrier concentrations and mobility extracted from Hall Effect measurements. Firstly, the metal precursor films were fabricated in multi-target sputtering system, then they were sulfurized inside the tubular furnace in order to obtain the CZTS compound. X-ray diffraction and Raman spectroscopy measurements revealed the formation of kesterite structure. A good crystallinity and grain compactness of the films were determined by scanning electron microscopy (SEM). Electrical properties were measured by van der Pauw techniques. Hall effect measurements showed the p-type semiconductor behavior for all samples at room temperature. Also, optical properties including absorption coefficient, spectral transmission, and optical band gap were determined to characterize CZTS thin films.Master Thesis Growth of Cu2znsns4 Absorber Layer on Flexible Metallic Substrates for Thin Film Solar Cell Applications(Izmir Institute of Technology, 2014) Yazıcı, Şebnem; Aygün, Gülnur; Aygün Özyüzer, Gülnur; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThis thesis presents the results of the fabrication and investigation of Cu2ZnSnS4 (CZTS) p-type semiconducting compound on rigid and flexible substrates, such as soda lime glass, ceramics and metallic foil substrates. The CZTS material was obtained by using a two-stage method. In the first stage, the metallic precursor was deposited by using DC magnetron sputtering technique then, the sulfurization process followed it. The particular emphasis has been placed on the distinctive substrate behavior in the growth procedure, including the microstructural characterization of the CZTS structure and the investigations of the back contact/CZTS interface. Additionally, the effect of the high temperature sulfur treatment on the formation mechanism of CZTS structure inves-tigated elaborately. Moreover, electrical properties including the temperature dependent electrical conductivity, carrier concentrations and mobility extracted from Hall Effect measurements, and optical properties including absorption coefficient, spectral transmis-sion, and optical band gap have been determined to characterize CZTS thin films. Raman spectroscopy and XPS analysis of the sulfurized thin films revealed that, except for the presence of Sn-based secondary phases, nearly pure CZTS thin films were obtained. Additionally, the intense and sharp XRD diffraction peak from the (112) plane provided evidence of good crystallinity. EDS analysis indicated sufficient sulfur content but poor Zn atomic weight percentage in the films. Absorption and band-gap energy analysis were carried out to confirm the suitability of CZTS thin films for the usage as the absorber layer in solar cell applications. Finally, Hall Effect measurements showed the p-type semiconductor behavior of the CZTS samples. We aimed to investi-gate the role of the flexible titanium and molybdenum foil substrates in the growth mechanism of CZTS thin films. The crack formation in the CZTS layer on the Mo foils were detected, which is an indication of the incompatible thermal expansion coefficient of Mo with the CZTS structure.