Influence of GaN template thickness and morphology on AlxGa1−xN luminescence properties

• Published in: Optical materials Vol. 35; no. 5; pp. 988 - 992
• Main Authors: Halidou, I., Touré, A., Nguyen, L., Bchetnia, A., El Jani, B.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.03.2013; Elsevier
• Subjects: AlGaN; Aluminum; Aluminum gallium nitrides; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Energy-dispersive X-ray spectroscopy; Exact sciences and technology; Excitation spectra; Fundamental areas of phenomenology (including applications); Gallium nitrides; Iii-v semiconductors; Metalorganic vapor phase epitaxy; Morphology; Optical materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optics; Other nonlinear optical materials; photorefractive and semiconductor materials; Photoluminescence; Physics; Silicon substrates; SiN treatment; Three dimensional; Two dimensional; Energy-dispersive X-ray spectroscopy; SiN treatment; Metalorganic vapor phase epitaxy; Photoluminescence; AlGaN; Gallium Nitrides; Atmospheric pressure; Ternary compounds; Luminescence; Line widths; Binary compounds; VPE; X-ray spectra; High temperature; X-ray spectroscopy; Excitons; MOVPE method; Optical properties; Optical materials; III-V semiconductors
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2012.12.009

[Display omitted] ► AlxGa1−xN was grown on different GaN templates. ► Better luminescence property is obtained with 1.3μm-thick GaN template. ► Alloy disorder induces PL peak linewidth increase. ► A bowing parameter of 0.93eV is obtained. ► Two quenching mechanisms of the donor bound exciton PL-intensity are discussed. We report on AlxGa1−xN/GaN films grown by atmospheric pressure MOVPE in a home-made vertical reactor. The high temperature GaN template is grown using the Si/N treatment of (0001) sapphire substrate. This process presents advantages of ELO technology without its ex-situ complicated steps and induces 3D (initial stage) to 2D growth mode. We investigate systematically the effect of the template thickness and morphology on optical properties of the AlGaN films by photoluminescence (PL) measurements. Four 0.5μm-thick Al0.07Ga0.93N samples on different GaN templates have been studied. PL spectra, dominated at low temperature by the donor bound exciton emission line, show a better film quality when AlGaN is grown on 1.3μm-thick high quality 2D GaN template. Two quenching mechanisms of the donor bound exciton PL-intensity are discussed. The PL peak linewidth increases as a function of Al composition. A bowing parameter of 0.93eV is obtained from the band gap variations as a function of Al composition.