Ultraviolet detector materials and devices studied by femtosecond nonlinear optical techniques

M. Wraback*, H. Shen, P. Kung, M. Razeghi, J. C. Carrano, T. Li, J. C. Campbell

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations


Femtosecond nonlinear optical techniques have been employed in the study of carrier dynamics and transport in ultraviolet detector materials. Visible femtosecond pulses derived from the signal beam of a 250 kHz regenerative amplifier-pumped optical parametric amplifier were frequency doubled to obtain pulses tunable from 250 nm to 375 nm. Time-resolved reflectivity experiments indicate that the room-temperature carrier lifetime in GaN grown by double lateral epitaxial overgrowth (330 ps) is about 3 times longer than that of GaN grown on sapphire without benefit of this technique (130 ps). The electron velocity-field characteristic and saturation velocity in GaN have been obtained from time-resolved studies of electroabsorption in a GaN p-i-n diode. The peak steady-state velocity of 1.9×107 cm/s in this device occurs at 225 kV/cm. Time-resolved transmission measurements have been used to monitor ultrafast carrier relaxation phenomena in a thin AlGaN layer with bandgap in the solar blind region of the spectrum. Excitation intensity and wavelength dependent studies of the photoinduced bleaching decays suggest that they are primarily governed by trapping in a high density of sub-bandgap defect levels.

Original languageEnglish (US)
Pages (from-to)352-362
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2000
EventPhotodetectors: Materials and Devices V - San Jose, CA, USA
Duration: Jan 25 2000Jan 28 2000

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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