Optical sites in Eu- and Mg-codoped GaN grown by NH3-source molecular beam epitaxy

• Published in: Applied physics letters 2016-10, Vol.109 (15)
• Main Authors: Sekiguchi, Hiroto, Sakai, Masaru, Kamada, Takuho, Tateishi, Hiroki, Syouji, Atsushi, Wakahara, Akihiro
• Format: Article
• Language: English
• Subjects: Ammonia; Applied physics; Constitution; Epitaxial growth; Excitation; Gallium nitrides; Luminescence; Metalorganic chemical vapor deposition; Molecular beam epitaxy; Optical properties; Photoluminescence; Vapor phases
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4964519

Mg codoping can improve the luminescence properties of Eu-doped GaN. However, the enhanced optical sites differ depending on the fabrication method. In this study, the optical sites in Eu- and Mg-codoped GaN [GaN:(Eu, Mg)] grown by NH3-source molecular beam epitaxy (MBE) were evaluated. The optical properties of an Eu–Mg-related site grown by NH3-MBE were highly stable against thermal annealing. Although the luminescence at sites A (622.3 and 633.8 nm) and B (621.9 and 622.8 nm) was dominant under indirect excitation of Eu ions through GaN, four different optical site groups in addition to sites A and B were observed under resonant excitation. These optical sites are inconsistent with the Eu–Mg-related sites reportedly observed in GaN:(Eu, Mg) fabricated by organometallic vapor phase epitaxy, indicating that the optical site constitution strongly depends on the growth method. Furthermore, site A, with a high cross section, contributed to as much as 22% of the total photoluminescence (PL) integrated intensity for GaN:(Eu, Mg) grown by NH3-MBE, which resulted in a high PL intensity.