Terahertz radiation by spontaneous polarization fields in InN

K. I. Lin, J. T. Tsai, J. S. Hwang, M. C. Chen

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Terahertz (THz) radiation is measured from InN excited by femtosecond optical pulses at 790 nm. The InN sample is grown by metalorganic chemical vapor deposition. The InN surface shows typical grain like morphology often observed in N-polar InN. The polarity of the THz radiation field from InN is opposite to that from p-InAs, whose radiation mechanism is dominated by the photo-Dember effect, and is same as that from p-GaAs indicating that the dominant radiation mechanism in InN is the drift current induced by the internal electric field at low-density excitation. In addition, since no azimuthal angle dependence of the THz radiation is observed, the optical rectification effect is ruled out. The lattice constant c=5.7091 for the InN epilayer is determined by θ2θ scan of X-ray diffraction. This implies that the InN epilayer is fully relaxed. Therefore, there is no piezoelectric polarization, and the internal electric field in the InN epilayer results from spontaneous polarization. According to the direction of the spontaneous polarization, the N polarity of the InN sample is confirmed.

Original languageEnglish
Pages (from-to)2669-2672
Number of pages4
JournalPhysica E: Low-Dimensional Systems and Nanostructures
Issue number10
Publication statusPublished - 2010 Sep

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics


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