RENiBEl Research Training Network
Rare Earth doped Nitrides for high Brightness Electroluminescence emitters
The RENiBEl project is a research Training Network funded by the European Commission. The contract (HPRN-CT-2001-00297) between the European Commission and network participants started on 1st April 2002 with a duration of 42 months. The key objective of the RENiBEl project is to understand the fundamental optical interactions of rare earth ions in GaN-based semiconductors in order to improve light emission efficiency and device performance.
Electroluminescence from rare earth doped nitride semiconductors shows promise for a variety of applications [1]. Strong room temperature luminescence can be observed in these materials for a variety of lanthanide dopants.
Modelling of the microscopic structure and properties of the defects involved in the luminescence presents a substantial challenge to current theoretical methods. While it is possible to investigate issues of defect stability using pseudo-potential based approaches [2], which avoid the problems of modelling strongly-correlated f-electron systems, this cannot address luminescence from these centres. Explicitly treating 4f electrons is beyond the reach of the usual mean-field methods normally employed in density-functional theory.
In an attempt to improve the theoretical description of these systems we present results using density-functional based calculations on the properties of selected lanthanides in wurtzite GaN. Both substitutional defects and complexes with native defects are considered.
We account for strong-correlation of the 4f shell using a variation of the LDA+U method, and discuss the role of spin-orbit coupling in defect properties.
Bibliography
1.A. J. Steckl, J. Heikenfeld, D. S. Lee, and M. Garter, Matter. Sci. Engr. B, 81 97-101 (2001).
2.J. S. Filhol, R. Jones, M. J. Shaw, P. R. Briddon, Appl. Phys. Letts. 84 2841-2843 (2004).
Recent Conference Papers and Contributions
15-19 Mai, Edimburgh, AFOSR Wide Band Gap Ferromagnetic Semiconductors Workshop: http://www.afosr.af.mil/currentw.htm
24-29 Juli, Awaji Inseln, Japan, ICDS-23 International Conference on Defects in Semiconductors: http://www.sanken.osaka-u.ac.jp/icds23/
18-23 September, Pittsburgh, ICSCRM 2005: http://cmsplus.tms.org/CMS/CMSPlus.nsf?OpenDatabase
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