Direct spontaneous growth and interfacial structural properties of inclined GaN nanopillars on r-plane sapphire
Abstract
The spontaneous growth of GaN nanopillars (NPs) by direct plasma-assisted molecular beam epitaxy on nitridated r-plane sapphire substrates has been studied. The emanation of metal-polarity NPs from inside an a-plane nonpolar GaN film was found to depend on both the substrate nitridation and the growth conditions. The density of NPs increased with increasing the duration of the nitridation process and the power applied on the radio-frequency plasma source, as well as the III/V flux ratio, while variation of the first two parameters enhanced the roughness of the substrate's surface. Transmission electron microscopy (TEM) techniques were employed to reveal the structural characteristics of the NPs and their nucleation mechanism from steps on the sapphire surface and/or interfacial semipolar GaN nanocrystals. Lattice strain measurements showed a possible Al enrichment of the first 5–6 monolayers of the NPs. By combining cross-sectional and plan-view TEM observations, the three-dimensional model of the NPs was constructed. The orientation relationship and interfacial accommodation between the NPs and the nonpolar a-plane GaN film were also elucidated. The NPs exhibited strong and narrow excitonic emission, suggesting an excellent structural quality.
- Authors:
-
- Microelectronics Research Group (MRG), IESL, FORTH, P.O. Box 1385, GR 711 10 Heraklion Crete, Greece and Physics Department, University of Crete, GR 710 03 Heraklion Crete (Greece)
- Physics Department, Aristotle University of Thessaloniki, GR 541 24, Thessaloniki (Greece)
- Publication Date:
- OSTI Identifier:
- 22490728
- Resource Type:
- Journal Article
- Journal Name:
- Journal of Applied Physics
- Additional Journal Information:
- Journal Volume: 117; Journal Issue: 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; FILMS; GALLIUM NITRIDES; METALS; MOLECULAR BEAM EPITAXY; NANOSTRUCTURES; NITRIDATION; NUCLEATION; ORIENTATION; PLASMA; RADIOWAVE RADIATION; ROUGHNESS; SAPPHIRE; STRAINS; SUBSTRATES; SURFACES; TRANSMISSION ELECTRON MICROSCOPY
Citation Formats
Adikimenakis, A., Aretouli, K. E., Tsagaraki, K., Androulidaki, M., Georgakilas, A., Lotsari, A., Dimitrakopulos, G. P., E-mail: gdim@auth.gr, Kehagias, Th., and Komninou, Ph. Direct spontaneous growth and interfacial structural properties of inclined GaN nanopillars on r-plane sapphire. United States: N. p., 2015.
Web. doi:10.1063/1.4923034.
Adikimenakis, A., Aretouli, K. E., Tsagaraki, K., Androulidaki, M., Georgakilas, A., Lotsari, A., Dimitrakopulos, G. P., E-mail: gdim@auth.gr, Kehagias, Th., & Komninou, Ph. Direct spontaneous growth and interfacial structural properties of inclined GaN nanopillars on r-plane sapphire. United States. https://doi.org/10.1063/1.4923034
Adikimenakis, A., Aretouli, K. E., Tsagaraki, K., Androulidaki, M., Georgakilas, A., Lotsari, A., Dimitrakopulos, G. P., E-mail: gdim@auth.gr, Kehagias, Th., and Komninou, Ph. 2015.
"Direct spontaneous growth and interfacial structural properties of inclined GaN nanopillars on r-plane sapphire". United States. https://doi.org/10.1063/1.4923034.
@article{osti_22490728,
title = {Direct spontaneous growth and interfacial structural properties of inclined GaN nanopillars on r-plane sapphire},
author = {Adikimenakis, A. and Aretouli, K. E. and Tsagaraki, K. and Androulidaki, M. and Georgakilas, A. and Lotsari, A. and Dimitrakopulos, G. P., E-mail: gdim@auth.gr and Kehagias, Th. and Komninou, Ph.},
abstractNote = {The spontaneous growth of GaN nanopillars (NPs) by direct plasma-assisted molecular beam epitaxy on nitridated r-plane sapphire substrates has been studied. The emanation of metal-polarity NPs from inside an a-plane nonpolar GaN film was found to depend on both the substrate nitridation and the growth conditions. The density of NPs increased with increasing the duration of the nitridation process and the power applied on the radio-frequency plasma source, as well as the III/V flux ratio, while variation of the first two parameters enhanced the roughness of the substrate's surface. Transmission electron microscopy (TEM) techniques were employed to reveal the structural characteristics of the NPs and their nucleation mechanism from steps on the sapphire surface and/or interfacial semipolar GaN nanocrystals. Lattice strain measurements showed a possible Al enrichment of the first 5–6 monolayers of the NPs. By combining cross-sectional and plan-view TEM observations, the three-dimensional model of the NPs was constructed. The orientation relationship and interfacial accommodation between the NPs and the nonpolar a-plane GaN film were also elucidated. The NPs exhibited strong and narrow excitonic emission, suggesting an excellent structural quality.},
doi = {10.1063/1.4923034},
url = {https://www.osti.gov/biblio/22490728},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 24,
volume = 117,
place = {United States},
year = {Sun Jun 28 00:00:00 EDT 2015},
month = {Sun Jun 28 00:00:00 EDT 2015}
}