The linewidth of the luminescence should be the reflection of the system disorder, and the natural way of thinking is to associate this disorder with local variation of In composition and/or quantum wells thickness. Problem of the emission linewidth of InGaN quantum structures has been discussed over last two decades. In the early work of O’Donnel et al.1, the remarkable, universal character of the emission broadening in InGaN quantum wells and epilayers was reported. Authors argued that since the line broadening is apparently independent of the growth method, it must reflect an inherent feature of these structures. Indeed, up to our knowledge there is presently no data showing a direct relation between the emission linewidth and microscopic landscape of InGaN structures. To look more closely on the origin of emission line broadening we performed cathodoluminescence (CL) mapping, using Hitachi SU-70 scanning electron microscope equipped with Horiba Jobin Yvon optical detection system. We analyzed InGaN/GaN quantum wells in wide range of In content.
Our measuments show that over large span of image diameter, the cathodoluminescence linewidth remains almost constant, meaning that what we perceive as the visible In fluctuation landscape is practically irrelevant. Most likely the observed source of broadening is related to submicron size effects related to strong carriers localization.
1. K. P. O’Donnell, T. Breitkopf, H. Kalt, W. Van der Stricht, I. Moerman, P. Demeester, and P. G. Middleton, “Optical linewidths of InGaN light emitting diodes and epilayers”, Appl. Phys. Lett. 70, 1843 (1997)
Lucja Marona, Przemyslaw Wisniewski, Robert Czernecki, and Piotr Perlin, "Do we know the cause of luminescence broadening in InGaN quantum wells? (Conference Presentation)," Proc. SPIE 10532, Gallium Nitride Materials and Devices XIII, 105320O (Presented at SPIE OPTO: January 30, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2289550.5751531101001.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations.