Indirect interband transition in hexagonal GaN

• Published in: Journal of physics. D, Applied physics Applied physics, 2011-02, Vol.44 (7), p.075105
• Main Authors: Lancry, O, Farvacque, J-L, Pichonat, E, Gaquière, C
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Iii-v and ii-vi semiconductors; Iii-v semiconductors; Infrared and raman spectra and scattering; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/44/7/075105

In this paper, we report on optical investigations with Raman experiment to underline a new ultraviolet (UV) luminescence band in hexagonal gallium nitride (GaN) at 4.56 eV. GaN is a direct band gap semiconductor, the photoluminescence peak corresponding to the energy gap at 3.43 eV dominates the spectrum. Nevertheless, other electronic interband transitions can appear on the spectrum: the electronic indirect interband transitions. We attribute one of them to the observed new photoluminescence band at 4.56 eV. This interpretation is supported by photoluminescence spectra obtained on three different samples at room temperature and at −50 °C with UV excitation source: mbd-266 nm solid laser (4.66 eV) and by the study of three criteria: the partly opposite parities of initial and final wave function, the implication of acoustic phonons and temperature control.