| Partner: A. Lotsari |
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Ostatnie publikacje
| 1. | Young T.D., Jurczak G., Lotsari A.♦, Dimitrakopulos G.P.♦, Komninou Ph.♦, Dłużewski P., A study of the piezoelectric properties of semipolar 11(2)over-bar2 GaN/AlN quantum dots, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, ISSN: 0370-1972, DOI: 10.1002/pssb.201552156, Vol.252, No.10, pp.2296-2303, 2015 Streszczenie: GaN quantum dots grown in (inline image)’orientated AlN are studied. The inline image-nucleated quantum dots exhibit rectangular- or trapezoid-based truncated pyramidal morphology. Another quantum dot type orientated on inline image is reported. Based on high-resolution transmission microscopy and crystal symmetry, the geometry of inline image-orientated quantum dots is proposed. A piezoelectric model is used within a finite element method to determine and compare the strain-state and electrostatic potential associated with the quantum dot morphology and an estimation of the band-edge energy is made. We report on some novel properties of the inline image-orientated quantum dot, including mixed strain-states and strain-state bowing. Słowa kluczowe: III–V semiconductors, AlN, GaN, nanostructures, piezoelectric properties, quantum dots Afiliacje autorów:
|  | 20p. | |||||||||||||||||||||||||||||||||||||||||||||
| 2. | Dimitrakopulos G.P.♦, Kalesaki E.♦, Kioseoglou J.♦, Kehagias T.♦, Lotsari A.♦, Lahourcade L.♦, Monroy E.♦, Häusler I.♦, Kirmse H.♦, Neumann W.♦, Jurczak G., Young T.D., Dłużewski P., Komninou Ph.♦, Karakostas T.♦, Morphology and strain of self-assembled semi-polar GaN quantum dots in (1112) AlN, JOURNAL OF APPLIED PHYSICS, ISSN: 0021-8979, DOI: 10.1063/1.3506686, Vol.108, pp.104304-1-9, 2010 Streszczenie: GaN quantum dots (QDs) grown in semipolar (11-22) AlN by plasma-assisted molecular-beam epitaxy were studied by transmission electron microscopy (TEM) and scanning transmission electron microscopy techniques. The embedded (11-2)-grown QDs exhibited pyramidal or truncated-pyramidal morphology consistent with the symmetry of the nucleating plane, and were delimited by nonpolar and semipolar nanofacets. It was also found that, in addition to the (11-22) surface, QDs nucleated at depressions comprising {10-11} facets. This was justified by ab initio density functional theory calculations showing that such GaN/AlN facets are of lower energy compared to (11-22). Based on quantitative high-resolution TEM strain measurements, the three-dimensional QD strain state was analyzed using finite-element simulations. The internal electrostatic field was then estimated, showing small potential drop along the growth direction, and limited localization at most QD interfaces. Słowa kluczowe: Quantum dots, Transmission electron microscopy, III-V semiconductors, High resolution transmission electron microscopy, Epitaxy Afiliacje autorów:
| | 32p. |