Carrier dynamics in AlN and GaN epilayers at the elevated temperatures

N. Nepal, K. B. Nam, J. Li, J. Y. Lin, H. X. Jiang

Research output: Contribution to journalConference article

1 Scopus citations

Abstract

Deep ultraviolet (UV) photoluminescence (PL) spectroscopy has been employed to study the optical properties and carrier dynamics in AlN and GaN epilayers at temperatures from 10 to 800 K. The parameters that describe the temperature variation of the energy bandgap (α and β, or a B and θ) and linewidth broadening have been obtained and are compared with the previously reported values in AlN and GaN obtained by different measurement methods in narrower temperature ranges. Our experimental results demonstrate that the broader temperature range of measurements is necessary to obtain accurate values of these parameters, particularly for AlN. The phonon-carrier interactions were also investigated in both AlN and GaN epilayers. At low temperatures, the linewidth of PL emission lines increases with temperature due to the electron-acoustic phonon interaction. The electron-LO phonon interaction becomes important above 200 K and eventually dominant at high temperatures in both AlN and GaN. The temperature dependencies of the decay lifetimes were investigated up to 500 K, from which free excitons and free carriers interactions are discussed for AlN and GaN epilayers. The implications of our findings to the optoelectronic and electronic device applications at elevated temperatures are discussed.

Original languageEnglish
Article number17
Pages (from-to)119-125
Number of pages7
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5725
DOIs
StatePublished - 2005
EventUltrafast Phenomena in Semiconductors and Nanostructure - San Jose, CA, United States
Duration: Jan 24 2005Jan 27 2005

Keywords

  • AlN
  • Carrier dynamics
  • GaN
  • High temperature
  • Optical transitions
  • Time-resolved PL
  • UV light emitters
  • Ultrafast

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