Partner: A. Lotsari

Aristotle University of Thessaloniki (GR)

Recent publications
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
Abstract:

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.

Keywords:

III–V semiconductors, AlN, GaN, nanostructures, piezoelectric properties, quantum dots

Affiliations:
Young T.D.-IPPT PAN
Jurczak G.-IPPT PAN
Lotsari A.-Aristotle University of Thessaloniki (GR)
Dimitrakopulos G.P.-Aristotle University of Thessaloniki (GR)
Komninou Ph.-Aristotle University of Thessaloniki (GR)
Dłużewski P.-IPPT PAN
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
Abstract:

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.

Keywords:

Quantum dots, Transmission electron microscopy, III-V semiconductors, High resolution transmission electron microscopy, Epitaxy

Affiliations:
Dimitrakopulos G.P.-Aristotle University of Thessaloniki (GR)
Kalesaki E.-Aristotle University of Thessaloniki (GR)
Kioseoglou J.-Aristotle University of Thessaloniki (GR)
Kehagias T.-Aristotle University of Thessaloniki (GR)
Lotsari A.-Aristotle University of Thessaloniki (GR)
Lahourcade L.-CNRS (FR)
Monroy E.-CNRS (FR)
Häusler I.-Humboldt-Universität zu Berlin (DE)
Kirmse H.-Humboldt-Universität zu Berlin (DE)
Neumann W.-Humboldt-Universität zu Berlin (DE)
Jurczak G.-IPPT PAN
Young T.D.-IPPT PAN
Dłużewski P.-IPPT PAN
Komninou Ph.-Aristotle University of Thessaloniki (GR)
Karakostas T.-Aristotle University of Thessaloniki (GR)