X-ray diffraction analysis and scanning micro-Raman spectroscopy of structural irregularities and strains deep inside the multilayered InGaN/GaN heterostructure

• Published in: Semiconductors (Woodbury, N.Y.) Vol. 44; no. 9; pp. 1199 - 1210
• Main Authors: Strelchuk, V. V., Kladko, V. P., Avramenko, E. A., Kolomys, O. F., Safryuk, N. V., Konakova, R. V., Yavich, B. S., Valakh, M. Ya, Machulin, V. F., Belyaev, A. E.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.09.2010; Springer
• Subjects: ALLOYS; Analysis; CHARGE CARRIERS; CHEMICAL COATING; CHEMICAL VAPOR DEPOSITION; COHERENT SCATTERING; CORUNDUM; CRYSTAL DEFECTS; CRYSTAL GROWTH METHODS; CRYSTAL STRUCTURE; CRYSTALS; DEPOSITION; DIFFRACTION; DIMENSIONS; DISLOCATIONS; DISTRIBUTION; EMISSION; EPITAXY; GALLIUM COMPOUNDS; GALLIUM NITRIDES; LASER SPECTROSCOPY; LAYERS; LIGHT EMITTING DIODES; LINE DEFECTS; Liquors; Low-Dimensional Systems; Magnetic Materials; Magnetism; MATERIALS SCIENCE; MINERALS; NANOSTRUCTURES; NITRIDES; NITROGEN COMPOUNDS; ORGANIC COMPOUNDS; ORGANOMETALLIC COMPOUNDS; OXIDE MINERALS; Physics; Physics and Astronomy; PNICTIDES; QUANTUM WELLS; RAMAN SPECTROSCOPY; SAPPHIRE; SCATTERING; SEMICONDUCTOR DEVICES; SEMICONDUCTOR DIODES; SPATIAL DISTRIBUTION; SPECTROSCOPY; Spectrum analysis; STRAINS; SUBSTRATES; SUPERLATTICES; SURFACE COATING; THICKNESS; X-RAY DIFFRACTION; X-rays; Nitride Layer; Epitaxial Layer; Phonon Band; Longitudinal Optical; Buffer Layer
• ISSN: 1063-7826; 1090-6479
• DOI: 10.1134/S1063782610090174

High-resolution X-ray diffraction analysis and scanning confocal Raman spectroscopy are used to study the spatial distribution of strains in the In x Ga 1 − x N/GaN layers and structural quality of these layers in a multilayered light-emitting diode structure produced by metal-organic chemical vapor deposition onto (0001)-oriented sapphire substrates. It is shown that elastic strains almost completely relax at the heterointerface between the thick GaN buffer layer and In x Ga 1 − x N/GaN buffer superlattice. It is established that the GaN layers in the superlattice are in a stretched state, whereas the alloy layers are in a compressed state. In magnitude, the stretching strains in the GaN layers are lower than the compressive strains in the InGaN layers. It is shown that, as compared to the buffer layers, the layers of the superlattice contain a smaller number of dislocations and the distribution of dislocations is more randomly disordered. In micro-Raman studies on scanning through the thickness of the multilayered structure, direct evidence is obtained for the asymmetric gradient distributions of strains and crystal imperfections of the epitaxial nitride layers along the direction of growth. It is shown that the emission intensity of the In x Ga 1 − x N quantum well is considerably (more than 30 times) higher than the emission intensity of the GaN barrier layers, suggesting the high efficiency of trapping of charge carriers by the quantum well.