Abstract
In this work, we investigate the mechanisms that control the electroluminescence from p-i-n heterostructures containing self-assembled In0.5Ga0.5As quantum dots embedded inside a GaAs/Al0.3Ga0.7As quantum well as a function of temperature and applied bias. Our results reveal that the carrier dynamics at the interface between the quantum dot and the quantum well play a crucial role in the electroluminescence emission. At low temperatures, two distinct emission bands are observed. Initially at low bias current, we observe broad emissions from the quantum wells and wetting layers. Another dominant and sharp emission at lower energy arises from the quantum dots, but only at higher bias currents. We discuss how a potential barrier between the quantum dots and quantum well can control the density of injected carriers undergoing optical recombination. We have also investigated the role of carrier capture and escape, quantum-confined stark effect and band-filling effects in the electroluminescence emission. In addition, we demonstrate how measurements of temporal coherence of individual spectral peaks, can detect the presence of Auger recombination in quantum dots under high injection currents. Interestingly, a significant increase in the temporal coherence of quantum dot emissions is observed, which could be due to a decrease in Auger recombination with increasing temperature.
Highlights
Quantum dot (QD) laser is a device of great interest in optoelectronics because of its expected energy efficiency [1], temperature stability, and spectral sharpness, which can be better than existing quantum well (QW) lasers [2]
We will refer to the emission at 1.47 eV as QW-WL emission as it has the contributions of QD wetting layers
It is evident from figure 1(c) that at low bias currents, the emission of the QW-WL peak is more prominent than the actual In0.5Ga0.5As QD peak
Summary
Quantum dot (QD) laser is a device of great interest in optoelectronics because of its expected energy efficiency [1], temperature stability, and spectral sharpness, which can be better than existing quantum well (QW) lasers [2]. Through improvements in material engineering, growth techniques and device level structural modification, QD lasers are getting more efficient and applicable for various technologies [6,7,8]. One such modification for extra confinement of charge carriers is embedding quantum dots within quantum well (QD-QW) system [9, 10]. The temporal coherence of the EL of sample without DBR is analysed in the high current density regime using a Michelson interferometer. Thereby, we explain how Auger recombination (AR) affects optical coherence of the EL from the In0.5Ga0.5As QDs in high bias current regime. The temporal coherence of QD emission increases with increasing temperature
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
