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Resonant light delay in GaN with ballistic and diffusive propagation
T V Shubina1, M M Glazov, A A Toropov
1Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia.
Physical Review Letters
|March 21, 2008
Summary
Light propagation in Gallium Nitride (GaN) significantly slows near a neutral-donor bound exciton (BX) resonance, reaching velocities as low as 2100 km/s. This phenomenon involves resonant scattering and polariton propagation, creating both ballistic and diffusive light components.
Area of Science:
- Solid-state physics
- Optics
- Materials science
Background:
- Light propagation in semiconductors is crucial for optoelectronic devices.
- Gallium Nitride (GaN) is a key material for high-frequency and optoelectronic applications.
- Understanding light-matter interactions at resonant frequencies is essential for advanced optical control.
Purpose of the Study:
- To investigate the phenomenon of light propagation delay in bulk Gallium Nitride (GaN).
- To analyze the resonant behavior of light delay near a neutral-donor bound exciton (BX).
- To explain the observed light components (ballistic and diffusive) near the BX resonance.
Main Methods:
- Time-of-flight spectroscopy was employed to measure light propagation times.
- Experimental data was analyzed to determine the velocity of light in GaN.
- Theoretical modeling based on optical dispersion, resonant scattering, and polariton propagation was used for explanation.
Main Results:
- A significant delay in light propagation through bulk GaN was observed.
- The delay showed a resonant increase as photon energy approached the neutral-donor bound exciton (BX) energy.
- Light velocities as low as 2100 km/s were recorded near the BX resonance.
- Transmitted light exhibited both ballistic and diffusive components in the vicinity of the BX resonance.
Conclusions:
- Resonant light scattering by the neutral-donor bound exciton (BX) strongly influences light propagation in GaN.
- The observed phenomenon can be quantitatively explained by considering optical dispersion alongside polariton propagation and resonant scattering.
- This study provides insights into controlling light velocity in semiconductors.
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