Correlation of optical and structural properties of GaN/AlN multi-quantum wells—Ab initio and experimental study
- Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw (Poland)
- Institute of Physics Polish Academy of Sciences, Al. Lotników 32/46, 01-142 Warsaw (Poland)
- Université Grenoble-Alpes, 38000 Grenoble (France)
The results of comprehensive theoretical and experimental study of binary GaN/AlN multi-quantum well (MQW) systems oriented along polar c-direction of their wurtzite structure are presented. A series of structures with quantum wells and barriers of various thicknesses were grown by plasma-assisted molecular-beam epitaxy and characterized by x-ray diffraction and transmission electron microscopy. It was shown that in general the structures of good quality were obtained, with the defect density decreasing with increasing quantum well thickness. The optical transition energies in these structures were investigated comparing experimental measurements with ab initio calculations of the entire GaN/AlN MQW structure depending on the QW widths and strains, allowing for direct determination of the energies of optical transitions and the electric fields in wells/barriers by electric potential double averaging procedure. Photoluminescence (PL) measurements revealed that the emission efficiency as well as the shape of luminescence spectra correlated well with their structural quality. Additionally, due to the Quantum-Confined Stark Effect, the emission energy decreased by over 1 eV for quantum well thicknesses increasing from 1 nm up to 6 nm, and this effect was accompanied by the drastic drop of the PL efficiency. The experimental results are consistent with theoretical models. Comparison of experimental data obtained by a number of different characterization techniques with the density functional theory results received on the same geometry structure allowed to prove directly the theoretical models and to determine the polarization and the oscillator strengths in the AlN/GaN nitride systems for the first time.
- OSTI ID:
- 22494873
- Journal Information:
- Journal of Applied Physics, Vol. 119, Issue 1; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
ALUMINIUM NITRIDES
DENSITY FUNCTIONAL METHOD
EFFICIENCY
ELECTRIC FIELDS
ELECTRIC POTENTIAL
GALLIUM NITRIDES
MOLECULAR BEAM EPITAXY
OSCILLATOR STRENGTHS
PHOTOLUMINESCENCE
QUANTUM WELLS
STARK EFFECT
THICKNESS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION