GaAsN alloys belong to a class of semiconductors with fascinating physical properties. Indeed, a small amount of nitrogen incorporation in GaAs leads to a counterintuitive and large band-gap reduction, and to an unexpected sudden increase in the effective mass of electrons. Even more surprisingly, both electronic and structural changes can be reversed fully and in a tunable manner by hydrogen incorporation. In this paper, we combine x-ray absorption spectroscopy at the nitrogen edge with ab initio simulations to investigate the atomic geometry of N-H complexes in hydrogenated GaAsN. In this way, we provide experimental evidence that dihydrogen-nitrogen complexes with C2v symmetry are the most abundant species in hydrogenated GaAsN. This finding contradicts previous predictions of "in-line" N-H2* complexes as the predominant species, and accounts for recent infrared absorption experiments.
A dilute nitride compound for midinfrared optoelectronic devices
The growth of the antimony-rich dilute nitride alloys GaSbN, InGaSbN, and InGaAsSbN on GaSb substrates by solid-source molecular-beam epitaxy is reported. Bulk GaSbN layers are characterized by x-ray diffraction and the nitrogen incorporation is estimated to be close to 1%. A nitrogen-induced redshift of the photoluminescence peak wavelength as large as 110 meV is observed in In.15Ga.85Sb1−xNx/GaSb quantum wells. Photoluminescence emission at 77 K for an In0.3Ga0.7As0.1Sb0.9−xNx/Al0.25Ga0.75As0.02Sb0.98 multiple quantum well structure shows a 66 meV redshift due to nitrogen incorporation (2.33 μm emission wavelength), demonstrating the potential of this compound for midinfrared optoelectronic device applications
Growth and applications of Group III-nitrides
Recent research results pertaining to InN, GaN and AlN are reviewed, focusing on the different growth techniques of Group III-nitride crystals and epitaxial films, heterostructures and devices. The chemical and thermal stability of epitaxial nitride films is discussed in relation to the problems of deposition processes and the advantages for applications in high-power and high-temperature devices. The development of growth methods like metalorganic chemical vapour deposition and plasma-induced molecular beam epitaxy has resulted in remarkable improvements in the structural, optical and electrical properties. New developments in precursor chemistry, plasma-based nitrogen sources, substrates, the growth of nucleation layers and selective growth are covered. Deposition conditions and methods used to grow alloys for optical bandgap and lattice engineering are introduced. The review is concluded with a description of recent Group III-nitride semiconductor devices such as bright blue and white light-emitting diodes, the first blue-emitting laser, high-power transistors, and a discussion of further applications in surface acoustic wave devices and sensors.
ROSSANA HERNANDEZ
electronica del estado solido
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