A detailed optical study of several sets of AlN/GaN superlattice (SL) as well as AlGaN/GaN multiple quantum well (MQW) structures has been reported. In this study all materials were grown by MOCVD, as opposed to most previous studies where MBE was employed. Doublet excitonic features are observed in the PL spectra. They are explained in terms of discrete well width variations by one c-lattice parameter, i.e. two GaN monolayers. The residual photoluminescence (PL) line width in MQW structures is varying from about 10 meV for 15 Å QWs to > 15 meV for 45 Å QWs, also comparable to the best MBE structures reported. While the recombination process in undoped samples is excitonic, in MQWs doped with Si above about 5×1018 cm-3 free electrons (a 2DEG) are dominant, and the PL process is a free electrons-localized hole transition at low temperatures. The hole localization prevails up to very high n-doping, as was previously observed in bulk GaN. The hole localization is demonstrated via several experiments, including results on PL transient decay times and LO phonon coupling. Near surface band bending, due mainly to dopant depletion in doped structures or interaction with surface states in case of higher Al content in barriers, influence the distribution of electron filling among the QWs, making a detailed modeling of the spectral shape somewhat ambiguous. It is found that AlN barriers promote a strong room temperature PL signal from the QWs, as opposed to the case with AlGaN barriers.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/8460 must be provided.

1. Growth and optical properties of nitride dot-in-a-wire structure on Si substrate
2. Advance in Epitaxial Growth of SiC for High Power Devices
3. In situ X-ray diffraction monitoring of GaInN growth by metalorganic vapor phase epitaxy
4. Strain control in GaInN/GaN multiple quantum wells for high-performance green-light emitters
5. Comprehensive theoretical and experimental evaluation of the impact of the internal polarization fields on the optical emission energy of Si- doped GaN/AlGaN MQWs and superlattices
6. Effects of Si doping position on the emission energy and recombination dynamics of GaN/AlGaN multiple quantum wells
7. SiC - Present Status and Material Challanges