Luminescence of GaN single crystals prepared by heating a Ga melt in Na-N2 atmosphere

Takahiro Yamada, Hisanori Yamane, Takenari Goto, Takafumi Yao, Yongzhao Yao, Takashi Sekiguchi

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Colorless transparent prismatic crystals (0.5-2.0 mm long) and hopper crystals (1.0-2.5 mm long) of GaN were prepared by heating a Ga melt at 800°C in Na vapor under N2 pressures of 7.0 MPa for 300 h. The photoluminescence (PL) spectrum of a prismatic crystal at 4 K showed the emission peaks of neutral donor-bound excitan (D0-X) and free exciton (XA) at 3.472 eV and 3.478 eV, respectively, in the near band edge region. The full-width at half-maximum (FWHM) of (D0-X) peak was 1.9 meV. The emission peaks of a donor-acceptor pair transition (D 0-A0) and its phonon replicas were observed in a lower energy range (2.9-3.3 eV). The emission peaks of the D0-A0 and phonon replicas were also observed in the cathodoluminescence (CL) spectrum at 20 K. The (D0-X) PL peak of a hopper crystal at 4 K was at 3.474 eV (2.1 meV higher), having a FWHM of 6.1 meV which was over 3 times larger than that of the prismatic crystal. A strong broad band with a maximum intensity around 1.96 eV was observed for the hopper crystals in the CL spectrum at room temperature.

Original languageEnglish
Pages (from-to)713-717
Number of pages5
JournalCrystal Research and Technology
Issue number7
Publication statusPublished - 2007 Jul


  • Cathodoluminescence
  • GaN
  • Na flux method
  • Photoluminescence
  • Single crystal


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