AlGaN Epilayers (algan + epilayer)

Distribution by Scientific Domains


Selected Abstracts


Spatially resolved X-ray diffraction as a tool for strain analysis in laterally modulated epitaxial structures

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2009
A. Wierzbicka
Abstract Spatially resolved X-ray diffraction (SRXRD) is applied for micro-imaging of strain in laterally modulated epitaxial structures. In GaAs layers grown by liquid phase epitaxial lateral overgrowth (ELO) on SiO2 -masked GaAs substrates a downward tilt of ELO wings caused by their interaction with the mask is observed. The distribution of the tilt magnitude across the wings width is determined with ,m-scale spatial resolution. This allows measuring of the shape of the lattice planes in individual ELO stripes. If a large area of the sample is studied the X-ray imaging provides precise information on the tilt of an individual wing and its distribution. In heteroepitaxial GaSb/GaAs ELO layers local mosaicity in the wing area is found. By the SRXRD the size of microblocks and their relative misorientation were analyzed. Finally, the SRXRD technique was applied to study distribution of localized strain in AlGaN epilayers grown by MOVPE on bulk GaN substrates with AlN mask. X-ray mapping proves that by mask patterning strain in AlGaN layer can be easily engineered, which opens a way to produce thicker, crack-free AlGaN layers with a higher Al content needed in GaN-based laser diodes. All these examples show that high spatial and angular resolutions offered by SRXRD makes the technique a powerful tool to study local lattice distortions in semiconductor microstructures. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


MOVPE growth and characterization of a -plane AlGaN over the entire composition range

PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 7 2010
Masihhur R. Laskar
Abstract We report the metal organic vapor phase epitaxy (MOVPE) growth and characterization of non-polar (110) a -plane Alx Ga1,xN on (102) r -plane sapphire substrates over the entire composition range. Alx Ga1,xN samples with ,0.8 ,m thick layers and with x = 0, 0.18, 0.38, 0.46, 0.66, and 1.0 have been grown on r -plane sapphire substrates. The layer quality can be improved by using a 3-stage AlN nucleation layer and appropriate V/III ratio switching following nucleation. All a -plane AlGaN epilayers show an anisotropic in-plane mosaicity, strongly influenced by Al incorporation and growth conditions. Careful lattice parameter measurements show anisotropic in-plane strain that results in an orthorhombic distortion of the hexagonal unit cell, making Al composition determination from X-ray diffraction difficult. In general lower Al incorporation is seen in a -plane epilayers compared to c -plane samples grown under the same conditions. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Cathodoluminescence and electrophysical characterization of AlxGa1,xN epilayers

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
V. I. Kozlovsky
Abstract Cathodoluminescence (CL) of metalorganic vapor phase epitaxy (MOVPE) grown AlxGa1,xN epilayers on sapphire has been studied with x from 0.23 to 0.38. CL spectra of undoped and Si-doped AlGaN epilayers with the same alloy composition grown on thick GaN buffers have been compared. The free electron concentration in the doped samples has been measured to (1-1.6) 1017 cm,3 with a mobility of 84-115 cm2/Vs. CL spectra have been compared with deep level transient spectroscopy spectra. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Defect density dependence of luminescence efficiency and lifetimes in AlGaN active regions exhibiting enhanced emission from nanoscale compositional inhomogeneities

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006
G. A. Garrett
Abstract AlGaN epilayers grown by plasma-assisted molecular beam epitaxy and exhibiting high internal quantum efficiency (up to 30%) are incorporated into double-heterostructure devices grown on base layers of varying defect density. Growth of these AlGaN active layers, having increased emission from localization of carriers in regions of nanoscale compositional inhomogeneities, is found to benefit from base layers of reduced defect density, including thick AlGaN templates grown by hydride vapor phase epitaxy. Nonlinear radiative processes are observed at high optical excitation for layers grown on lower defect base layers. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]