Deep localization features of photoluminescence in narrow AlGaN quantum wells

• Published in: Optoelectronics letters 2024-12, Vol.20 (12), p.736-740
• Main Authors: Deng, Jianyang, Li, Rui, Guo, Ya’nan, Wang, Junxi, Wang, Chengxin, Ji, Ziwu
• Format: Article
• Language: English
• Subjects: Carrier recombination; High temperature; Lasers; Localization; Low temperature; Multi Quantum Wells; Optical Devices; Optics; Photoluminescence; Photonics; Physics; Physics and Astronomy; Quantum efficiency; Radiative recombination; Stark effect; Temperature dependence
• ISSN: 1673-1905; 1993-5013
• DOI: 10.1007/s11801-024-3296-x

The research prepared two deep ultraviolet (DUV) AlGaN-based multiple quantum well (MQW) samples with the same Al content in the QWs but different well widths (3 nm for Sample A and 2 nm for Sample B). Photoluminescence (PL) measurements reveal that Sample A exhibits only one main PL peak across all measured temperatures, while Sample B displays one main PL peak at low temperatures and two distinct PL peaks at high temperatures. Furthermore, compared with Sample A, Sample B exhibits a more significant temperature-dependent PL peak wavelength blue shift relative to the Varshni curve, a more significant excitation power density-dependent PL peak blue shift accompanied by linewidth broadening, as well as a larger non-radiative recombination related activation energy and higher internal quantum efficiency ( IQE ). These findings can be explained by the observation that the narrower well width of Sample B induces a more pronounced effect of carrier localization than the wider well width of Sample A, due to the enhanced fluctuation in well width and reduced quantum-confined Stark effect (QCSE).