Terahertz emission and spectroscopy on InN epilayer and nanostructure

Hyeyoung Ahn*, C. L. Pan, S. Gwo

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

8 Scopus citations


We report a comprehensive study on THz emission and spectroscopy of indium nitride (InN) films and its nanorod arrays grown by plasma-assisted molecular beam epitaxy technique. For the enhancement of THz emission from InN, we demonstrated two method; firstly using nanorod arrays, which have large surface area for optical absorption and THz emission, and secondly using nonpolar InN film, of which the electric field is along the sample surface. We propose that a "screened" photo-Dember effect due to narrow surface electron accumulation layer of InN is responsible for the nanorod-size-dependent enhancement from InN nanorods. The primary THz radiation mechanism of nonpolar InN is found to be due to the acceleration of photoexcited carriers under the polarization-induced in-plane electric field. THz time-domain spectroscopy has been used to investigate THz conductivity and dielectric response of InN nanorod arrays and epitaxial film. The complex THz conductivity of InN film is well fitted by the Drude model, while the negative imaginary conductivity of the InN nanorods can be described by using a non-Drude model, which includes a preferential backward scattering due to defects in InN nanorods, or a Coulombic restoring force from charged defects.

Original languageEnglish
Article number72160T
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 5 May 2009
EventGallium Nitride Materials and Devices IV - San Jose, CA, United States
Duration: 26 Jan 200929 Jan 2009


  • Indium nitride
  • Nanostructures
  • Non-Drude model
  • THz emission
  • THz time-domain spectroscopy


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