Carrier recombination dynamics in green InGaN-LEDs with quantum-dot-like structures
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Carrier recombination dynamics in green InGaN-LEDs with quantum-dot-like structures Ming Tian1,2, Cangmin Ma1, Tao Lin1,*, Jianping Liu3, Devki N. Talwar4, Hui Yang3, Jiehua Cao1, Xinying Huang1, Wenlong Niu1, Ian T. Ferguson5, Lingyu Wan1,2, and Zhe Chuan Feng1,2,* 1
Laboratory of Optoelectronic Materials and Detection Technology, Center on Nanoenergy Research, Guangxi Key Laboratory for the Relativistic Astrophysics, School of Physics Science and Technology, Guangxi University, Nanning 530004, China 2 State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China 3 Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China 4 Department of Physics, University of North Florida, Jacksonville, FL 32224, USA 5 Southern Polytechnic College of Engineering and Engineering Technology, Kennesaw University, Kennesaw, GA 30144, USA
Received: 5 July 2020
ABSTRACT
Accepted: 15 September 2020
Exciton localization phenomena are considered here to comprehend the high internal quantum efficiency in InGaN/GaN multiple-quantum-well structures having discrete quantum dots (QDs) prepared by metal–organic-chemical-vapor deposition method on c-sapphire substrates. Spectroscopic results from the variable-temperature steady-state-photoluminescence and time-resolved photoluminescence (TRPL) are investigated. While the exciton localization is enhanced by strong localized states within the InGaN/GaN QDs–the impact of free carrier recombination cannot be ignored. The observed non-exponential decay in TRPL measurements is explained using a model by meticulously including localized exciton, non-radiative and free carrier recombination rates. A new method is proposed to calculate the internal quantum efficiency, which is supplementary to the traditional approach based on temperature-dependent photoluminescence measurement.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Introduction III-Nitride-based light-emitting diodes (LEDs) have attracted much attention in recent years due to their potential use in solid-state lighting, sensors, low
threshold lasers, etc. [1, 2]. Energy band gap tunability of InGaN with its prospective use as an active layer in LEDs has instigated both scientific and engineering interests for realizing full-color displays in the visible range. Based on these remarkable achievements, the 2014 Nobel Prize in physics was
Handling Editor: Kevin Jones.
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https://doi.org/10.1007/s10853-020-05343-6
J Mater Sci
awarded for GaN-related high efficient blue lightemitting diodes [3–5]. Consequently, the optoelectronic industry around the world is rapidly expanding where the III-N based quantum dots (QDs) [6], multi-quantum wells (MQWs) and/or superlattices (SLs) are being employed in LEDs, lasers, solar cells and medical imaging devices [7]. One must note that InxGa1-xN-based quantum wells (
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