Liquid-phase epitaxy of GaSe and potential application for wide frequency-tunable coherent terahertz-wave generation

Yutaka Oyama, Tadao Tanabe, Fumikazu Sato, Atsushi Kenmochi, Jun ichi Nishizawa, Tetsuo Sasaki, Ken Suto

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


GaSe is one of the most promising semiconductor crystals for wide frequency-tunable terahertz (THz) wave generation by photo mixing. The ε-type monocrystalline GaSe crystals were successfully grown by the liquid-phase epitaxy at constant and low (530-590 °C) growth temperatures under the controlled different selenium (Se) vapor pressures (PSe∼0-7.75 Torr). From the coherent THz-wave spectroscopy, the absorption spectra have shown different resonant frequencies and absorption coefficients due to the stoichiometry-dependent point defects which depend on the applied PSe. It is shown that the resonance in GaSe under PSe∼0 Torr shifts towards the lower THz frequencies compared with those under high PSe, maybe due to the degraded intermolecular interactions caused by the introduction of Se vacancy-related defects. The absorption coefficients (1-5 THz) decreased according to the increase of Se vapor pressure, thus the transparency of GaSe under higher PSe is improved by an amount of 25% compared with that of Bridgman-grown crystals. By using Bridgman-grown GaSe crystals, coherent-THz wave was generated by the difference frequency method (DFM) in a wide frequency range of 0.1-70 THz. Coherent-THz spectroscopy is a revolutionary method for the evaluation of molecular structures and defects in organic molecule also could be analyzed.

Original languageEnglish
Pages (from-to)1923-1928
Number of pages6
JournalJournal of Crystal Growth
Issue number7-9
Publication statusPublished - 2008 Apr 1


  • A1. Point defects
  • A2. Growth from solutions
  • B1. Gallium compounds
  • B2. Nonlinear optic materials

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry


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