TY - JOUR
T1 - Liquid-phase epitaxy of GaSe and potential application for wide frequency-tunable coherent terahertz-wave generation
AU - Oyama, Yutaka
AU - Tanabe, Tadao
AU - Sato, Fumikazu
AU - Kenmochi, Atsushi
AU - Nishizawa, Jun ichi
AU - Sasaki, Tetsuo
AU - Suto, Ken
PY - 2008/4/1
Y1 - 2008/4/1
N2 - 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.
AB - 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.
KW - A1. Point defects
KW - A2. Growth from solutions
KW - B1. Gallium compounds
KW - B2. Nonlinear optic materials
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U2 - 10.1016/j.jcrysgro.2007.11.205
DO - 10.1016/j.jcrysgro.2007.11.205
M3 - Article
AN - SCOPUS:41449098110
SN - 0022-0248
VL - 310
SP - 1923
EP - 1928
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
IS - 7-9
ER -