Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.
- 1 January 1997
- journal article
- Published by Springer Nature in MRS Internet Journal of Nitride Semiconductor Research
Abstract
Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.Keywords
This publication has 12 references indexed in Scilit:
- Strain-fluctuation effect on Raman spectraPhysical Review B, 1997
- Recombination dynamics of excitons and biexcitons in a hexagonal GaN epitaxial layerApplied Physics Letters, 1996
- Biexciton Luminescence from GaN Epitaxial LayersJapanese Journal of Applied Physics, 1996
- Optical studies of epitaxial GaN-based materialsPublished by SPIE-Intl Soc Optical Eng ,1996
- Optical properties of wurtzite GaN grown by low-pressure metalorganic chemical-vapor depositionJournal of Applied Physics, 1996
- Photoluminescence studies of band-edge transitions in GaN epitaxial layers grown by plasma-assisted molecular beam epitaxyJournal of Applied Physics, 1996
- Excitonic recombination in GaN grown by molecular beam epitaxyApplied Physics Letters, 1995
- Neutral-donor-bound exciton recombination dynamics in GaN grown by metalorganic chemical vapor depositionApplied Physics Letters, 1995
- Exciton lifetimes in GaN and GaInNApplied Physics Letters, 1995
- Dynamics of a band-edge transition in GaN grown by molecular beam epitaxyApplied Physics Letters, 1995