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Bas Y.,National Boron Research Institute | Demirel P.,Nanotechnology Research Center | Akin N.,Gazi Photonic Research Center | Baskose C.,Gazi Photonic Research Center | And 5 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2014

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. © 2014 Springer Science+Business Media New York.

Bas Y.,National Boron Research Institute | Tamer M.,Zirve University | Gultekin A.,Gazi Photonic Research Center | Ozturk M.K.,Gazi Photonic Research Center | And 3 more authors.
Gazi University Journal of Science | Year: 2015

Between n- GaN and p- AlGaN+GaN contacts, the blue light emitting diode (LED) structure with InGaN/GaN multiple quantum well has been grown using metalorganic vapor phase epitax (MOCVD) on c-oriented sapphire substrate. In order to research the strain and the stress of the lattice in crystal form, a reciprocal lattice space was mapped using a High Resolution X-Ray Diffractometer. In this study, by taking the qualities of the GaN epitaxial structure as reference point; relaxation, strain, hydrostatical strain and biaxial strain parameters are researched for the point defects taking the increasing temperatures into consideration. All parameters except the growth temperature of the InGaN layer were kept fixed for all samples. Depending on the growth temperature values, the results indicated a monotonous increasing-decreasing or decreasing-increasing manner. Additionally, the point defects of the blue LED structure on AlGaN layer have been compared to those of InGaN layer. While the lattice relax exchange of both layers were behaving in an opposite manner to each other; hydrostatic and biaxial strain exchanges were behaving in a parallel manner for both layers. As a result, since the points and the defects were carried from one layer to the other, the same tendencies were observed. © 2015, Gazi University Eti Mahallesi. All rights reserved.

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