Ultrafast optical probes, photoluminescence spectroscopy, and Raman spectroscopy have been applied to investigate carrier dynamics in nitride-based binary and ternary, and dilute nitride semiconductors. Carrier dynamics in the form of radiative and non-radiative lifetimes in GaN grown on pseudo-in situ TiN and in situ SiN nanonetworks by organometallic vapor phase epitaxy have been investigated and compared with those for freestanding GaN templates which constitute the benchmark values due to the high quality. Room temperature carrier lifetimes as long as 1.86 ns could be achieved with the use of TiN network templates. Time-resolved Raman spectroscopy has been employed to investigate the carrier dynamics, carrier transport and non-equilibrium optical phonons in In-containing nitride-based semiconductors. (1) It has been found that the energy loss rate in InxGa1-xAs 1-yNy is about 64 meV/ps suggesting that hot electrons lose their energy primarily to the GaAs-like LO phonons in this dilute nitride semiconductor. (2) Both the non-equilibrium electron distribution and the electron drift velocity in InGaN and InN have been measured. These experimental results are compared with ensemble Monte Carlo calculations and good agreement is found. (3) Our experimental results support the small bandgap value for InN (approximately 0.8 eV) and are inconsistent with the 0.8 eV luminescence emission being due to deep level radiative emission.
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Electrical and Electronic Engineering