Step-by-step capping and strain state of GaN/AlN quantum dots studied by grazing-incidence diffraction anomalous fine structure

Journal Article · Mon May 15 04:00:00 EDT 2006 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.73.2· OSTI ID:20788192

Coraux, J; Favre-Nicolin, V; Renevier, H ^[1]; Proietti, M G ^[2]; Daudin, B ^[1]

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1. Commissariat l'Energie Atomique, Departement de Recherche Fondamentale sur la Matiere Condensee, SP2M/NRS, 17 rue des martyrs, 38054 Grenoble Cedex 9 (France)
2. Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza, c. Pedro Cerbuna 12, 50009 Zaragoza (Spain)

The investigation of small-size embedded nanostructures, by a combination of complementary anomalous diffraction techniques, is reported. GaN quantum dots (QD's), grown by molecular beam epitaxy in a modified Stranski-Krastanow mode, are studied in terms of strain and local environment, as a function of the AlN cap layer thickness, by means of grazing-incidence anomalous diffraction. That is, the x-ray photon energy is tuned across the Ga absorption K edge which makes diffraction chemically selective. Measurement of hkl scans, close to the AlN (3030) Bragg reflection, at several energies across the Ga K edge, allows the extraction of the Ga partial structure factor, from which the in-plane strain of GaN QD's is deduced. From the fixed-Q energy-dependent diffracted intensity spectra, measured for diffraction-selected isostrain regions corresponding to the average in-plane strain state of the QD's, quantitative information regarding the composition and out-of-plane strain has been obtained. We recover the in-plane and out-of-plane strains in the dots. The comparison to the biaxial elastic strain in a pseudomorphic layer indicates a tendency to an overstrained regime.

• OSTI ID: 20788192
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 20 Vol. 73; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM NITRIDES
BRAGG REFLECTION
COMPARATIVE EVALUATIONS
CRYSTAL STRUCTURE
ENERGY DEPENDENCE
FINE STRUCTURE
GALLIUM NITRIDES
INTERFACES
LAYERS
MOLECULAR BEAM EPITAXY
PHOTONS
QUANTUM DOTS
SEMICONDUCTOR MATERIALS
STRAINS
STRESS ANALYSIS
STRUCTURE FACTORS
X RADIATION
X-RAY DIFFRACTION
X-RAY SPECTRA