Journal ArticleDOI
Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1−xN films
H. Angerer,D. Brunner,F. Freudenberg,Oliver Ambacher,Martin Stutzmann,R. Höpler,T. Metzger,E. Born,Günther Dollinger,Andreas Bergmaier,S. Karsch,H. J. Körner +11 more
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TLDR
In this article, the exact Al mole fraction and the biaxial strain of the alloys can be calculated by an additional determination of a, using asymmetric reflections, and the results obtained by x-ray diffraction and elastic recoil detection provide evidence for the validity of Vegard's law in the AlGaN system.Abstract:
AlxGa1−xN alloys were grown on c-plane sapphire by plasma-induced molecular beam epitaxy. The Al content x was varied over the whole composition range (0⩽x⩽1). The molar Al fraction was deduced from x-ray diffraction and for comparison by elastic recoil detection analysis. The composition of the alloys calculated from the lattice parameter c underestimates x. This is due to a deformation of the unit cell. The exact Al mole fraction and the biaxial strain of the alloys can be calculated by an additional determination of a, using asymmetric reflections. The results obtained by x-ray diffraction and elastic recoil detection provide evidence for the validity of Vegard’s law in the AlGaN system. In addition, the deviation of the band gap from a linear dependence on x was investigated. We found a downward bowing with a bowing parameter b=1.3 eV.read more
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Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures
Oliver Ambacher,Joseph A. Smart,James R. Shealy,Nils Weimann,K. Chu,M. J. Murphy,William J. Schaff,L.F. Eastman,Roman Dimitrov,L. Wittmer,Martin Stutzmann,W. Rieger,J. Hilsenbeck +12 more
TL;DR: In this article, the authors investigated the role of spontaneous and piezoelectric polarization on the carrier confinement at GaN/AlGaN and AlGaN/GaN interfaces.
Journal ArticleDOI
Two dimensional electron gases induced by spontaneous and piezoelectric polarization in undoped and doped AlGaN/GaN heterostructures
Oliver Ambacher,B. E. Foutz,Joseph A. Smart,James R. Shealy,Nils Weimann,K. Chu,M. J. Murphy,A. J. Sierakowski,William J. Schaff,L.F. Eastman,Roman Dimitrov,A. Mitchell,Martin Stutzmann +12 more
TL;DR: In this paper, a combination of high resolution x-ray diffraction, atomic force microscopy, Hall effect, and capacitance-voltage profiling measurements is used to calculate the polarization induced sheet charge bound at the AlGaN/GaN interfaces.
Journal ArticleDOI
III–nitrides: Growth, characterization, and properties
TL;DR: In this article, the splitting of the valence band by crystal field and spin-orbit interaction has been calculated and measured, and the measured values agree with the calculated values and the effects of strain on the splitting and optical properties have been studied in detail.
Journal ArticleDOI
Pyroelectric properties of Al(In)GaN/GaN hetero- and quantum well structures
Oliver Ambacher,Jacek A. Majewski,C. R. Miskys,A. Link,M. Hermann,Martin Eickhoff,Martin Stutzmann,Fabio Bernardini,Vincenzo Fiorentini,V. Tilak,B Schaff,L.F. Eastman +11 more
TL;DR: In this paper, it was shown that the macroscopic nonlinear pyroelectric polarization of wurtzite AlInN/GaN, InxGa1-xN and AlxIn1xN ternary compounds (large spontaneous polarization and piezoelectric coupling) dramatically affects the optical and electrical properties of multilayered Al(In)GaN/GAN hetero-, nanostructures and devices, due to the huge built-in electrostatic fields and bound interface charges caused by gradients in polarization at surfaces and heter
Journal ArticleDOI
X-ray diffraction of III-nitrides
Michelle A. Moram,M E Vickers +1 more
TL;DR: In this article, the basic principles of x-ray diffraction of thin films and areas of special current interest, such as analysis of non-polar, semipolar and cubic III-nitrides, are reviewed, along with the basic principle of X-ray diffusion of thin thin films, and some useful values needed in calculations, including elastic constants and lattice parameters.
References
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Candela‐class high‐brightness InGaN/AlGaN double‐heterostructure blue‐light‐emitting diodes
Abstract: Candela‐class high‐brightness InGaN/AlGaN double‐heterostructure (DH) blue‐light‐emitting diodes(LEDs) with the luminous intensity over 1 cd were fabricated As an active layer, a Zn‐doped InGaN layer was used for the DH LEDs The typical output power was 1500 μW and the external quantum efficiency was as high as 27% at a forward current of 20 mA at room temperature The peak wavelength and the full width at half‐maximum of the electroluminescence were 450 and 70 nm, respectively This value of luminous intensity was the highest ever reported for blue LEDs
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GaN, AlN, and InN: A review
S. Strite,Hadis Morkoç +1 more
TL;DR: The status of research on both wurtzite and zinc-blende GaN, AlN, and InN and their alloys including exciting recent results is reviewed in this paper.
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High-brightness InGaN blue, green and yellow light-emitting diodes with quantum well structures
TL;DR: In this paper, high-brightness blue, green and yellow light-emitting diodes (LEDs) with quantum well structures based on III-V nitrides were grown by metalorganic chemical vapor deposition on sapphire substrates.
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Superbright Green InGaN Single-Quantum-Well-Structure Light-Emitting Diodes
TL;DR: The luminous intensity of these green InGaN SQW LEDs (12 cd) was about 100 times higher than that of conventional green GaP LEDs (01 cd) as mentioned in this paper.
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Elastic constants of gallium nitride
TL;DR: The elastic constants of GaN have been determined using Brillouin scattering; in GPa they are: C11=390, C33=398, C44=105, C66=123, C12=145, and C13=106.