a b s t r a c tIn this study the effects of the annealing temperature on the InGaN/GaN solar cells with different In-contents grown on sapphire substrate by the Metal Organic Chemical Vapor Deposition (MOCVD) are analyzed by High Resolution X-ray Diffraction (HRXRD) and an Atomic Force Microscope (AFM). The plane angles, mosaic crystal sizes, mixed stress, dislocation intensities of the structure of the GaN and InGaN layers are determined. According to the test results, there are no general characteristic trends observed due to temperature at both structures. There are fluctuating failures determined at both structures as of 350°C. The defect density increased on the GaN layer starting from 350°C and reaching above 400°C. A similar trend is observed on the InGaN layer, too.

By using metal organic chemical vapor deposition technique, InGaN/GaN solar cell (SC) structure is deposited over sapphire (Al 2 O 3) wafer as GaN buffer and GaN epitaxial layers. Structural properties of InGaN/GaN/Al 2 O 3 SC structure is investigated by using high resolution X-ray diffraction technique dependent on In content. By using reciprocal space mapping, reciprocal space data are converted to w-θ data with a software. These w-θ data and full width at half maximum data are used for calculating lattice parameters. When compared with w-θ measurements in literature it is seen that especially a-lattice parameter is found very near to universal value from RSM. It is calculated as 3.2650 nm for sample A (S.A) GaN layer and 3.2570 nm for sample B (S.B) GaN layer on (105) asymmetric plane. Strain and stress calculations are made by using these lattice parameters. Strain and stress are calculated as 0.02363 and 8.6051 GPa for S.A GaN layer respectively. Other results are given in tables in the results and discussion section of this article. Edge, screw and mixed type dislocations are calculated as mosaic defects. All these calculations are made for two samples on (002) symmetric and (105) asymmetric planes. As a result it is seen that measurements by using RSM give more sensitive results. a-lattice parameter calculated with this technique is the best indicator of this result.

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Lattice parameters a-, c-, strain-stress analysis and thermal expansion coefficient of InGaN/GaN solar cell structures grown by MOCVD MOCVD ile büyütülen InGaN/GaN güneş hücresi yapısının a-,c-örgü parametreleri, zorlamagerilme analizi ve termal genleşme katsayısı Yazar(lar) (Author(s)) 0000-0003-3420-4936 ORCID 2 : : : : : 0000-0003-2953-1828 Bu makaleye şu şekilde atıfta bulunabilirsiniz(To cite to this article): Bilgili A.K., Akpinar O., Kurtulus G., Ozturk M.K., Ozcelik S. and Ozbay E., "Lattice parameters a-, c-, strain-stress analysis and thermal expansion coefficient of InGaN/GaN solar cell structures grown by MOCVD", Journal of Polytechnic, *(*): *, (*). (002), (004), (006) ve (121) düzlemleri için hesaplandı. HR-XRD'den elde edilen pik pozisyonlarının veri tabanlarındaki (database) pik pozisyonlarıyla neredeyse aynı olduğu görülmektedir. Hesaplamalardan elde edilen tüm sonuçlar bu çalışmanın bölümlerinde yer alan tablolarda verilmektedir. Bütün bu sonuçların farklı yazarlar tarafından yapılmış önceki eserlere ve gerçek değerlere uygun olduğu görülmektedir.

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