An Osaka Metropolitan University-led research team investigated the decay time of coherent longitudinal optical (LO) phonons both in a GaAs1−x Nx epilayer and in a GaAs single crystal to clarify the effects of dilute nitridation.
The team observed in terahertz time-domain spectroscopy that the terahertz electromagnetic waves, which are emitted from the coherent GaAs-like LO phonons, have a relatively long decay time in a GaAs1−x Nx epilayer in comparison with the terahertz waves from the coherent GaAs LO phonons in a semi-insulating GaAs single crystal.
This implies that alloy effects (mixed crystal effects) on the phonon Raman band broadening, which have a possibility of leading to the short decay time, hardly govern the decay time even in the present GaAs1−x Nx epilayer sample.