Cataloged from PDF version of article.In this paper, we study structural and morphological properties of metal-organic chemical vapour deposition-grown InGaN/GaN light emitting diode (LED) structures with different indium (In) content by means of high-resolution X-ray diffraction, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and current-voltage characteristic (I-V). We have found out that the tilt and twist angles, lateral and vertical coherence lengths of mosaic blocks, grain size, screw and edge dislocation densities of GaN and InGaN layers, and surface roughness monotonically vary with In content. Mosaic defects obtained due to temperature using reciprocal lattice space map has revealed optimized growth temperature for active InGaN layer of MQW LED. It has been observed in this growth temperature that according to AFM result, LED structure has high crystal dimension, and is rough whereas according to PL and FTIR results, bandgap energy shifted to blue, and energy peak half-width decreased at high values. According to I-V measurements, it was observed that LED reacted against light at optimized temperature. In conclusion, we have seen that InGaN MQW structure's structural, optical and electrical results supported one another

Structural, optical and electronic properties and elastic constants of Be 1-x Zn x S alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers-Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard's law. It is seen that results obtained from theory and experiments are all in agreement.

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.

6zturk 2 · 3 , S(.ileyman <;orekc:;:i4, Mehmet Tamer 3 · 7 , Yunus Ba~5 , Suleyman 6 zc:;:elik 2 · 3 , and Ekmel 6zbay 6 In this study are graded and non graded lnGaN/GaN samples grown on c-oriented sapphire substrate using the Metal Organic Chemical Vapour Deposition (MOCVD) technique. The structural and morphological properties of the grown lnGaN/GaN solar cell structures are analyzed using High Resolution X-ray Diffraction (HRXRD), atomic force microscopy (AFM) . Each structures c and a lattice parameters strain, biaxial strain , hydrostatic strain, stress , lattice relax, tilt angle, mosaic crystal size, dislocation densities of GaN and lnGaN layers are determined by XRD measurements . In accordance with these calculations , the effect of graded structure on the defects, are discussed . As a dramatic result; although values of full width at half maximum (FWHM) are broad, a considerable decrease at dislocations is noticed . The AFM observations have revealed that the two dimensional growth of the graded sample is more significant and its roughness value is lower. JV measurements shown that the performance of the graded structure is higher . It is determined that all test results are consistent with each other.

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