Phys. Rev. B 71, 035314 (2005) [5 pages]Chemically ordered AlxGa1−xN alloys: Spontaneous formation of natural quantum wellsReceived 8 March 2004; revised 6 October 2004; published 13 January 2005 We combine transmission electron microscopy, high-resolution x-ray diffraction, cathodoluminescence, and photoluminescence experiments with first-principles calculations to study the formation, thermodynamic stability, structural, and optical properties of chemically ordered AlxGa1−xN alloys (0<x<1). Our results reveal that group-III-nitride surfaces exhibit chemically highly sensitive adsorption sites at step edges and that these sites can be used to kinetically engineer chemically ordered AlxGa1−xN alloys. The ordered alloys have unique properties: (i) the band gap is redshifted up to 110 meV with respect to the disordered alloy of the same composition and (ii) the band gap reduction is caused by localization of the band edge wave functions in the GaN layer. Ordered AlxGa1−xN thus can be seen as a natural quantum well structure where electrons and holes are localized and confined in monolayer GaN quantum wells. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.71.035314
DOI:
10.1103/PhysRevB.71.035314
PACS:
78.67.−n, 61.14.−x, 71.20.−b
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