Temperature-Dependent carrier dynamics in InAsP/AlGaInP quantum dot lasers: Threshold current behavior and emission state contributions

Since 2015, significant research interest has focused on the development of InAsP quantum dot (QD) lasers grown on GaAs substrates. These self-assembled InAsP QD lasers, which emit in the wavelength range of 720–780 nm, have shown considerable potential in photonic applications such as photodynamic therapy, dual-wavelength light sources, and biophotonic sensing. Their emission characteristics make them particularly attractive for biomedical technologies and integrated photonics systems. Unlike the extensively studied InAs/GaAs systems, InAsP-based structures offer distinct material properties and advantages such as better tunability and potentially reduced defect densities due to lattice matching, contributing to a broader and more general understanding of QD laser physics and performance.

In this study, we investigate the temperature dependence of the threshold current density (Jth) in 2000 μm-long edge-emitting laser devices fabricated using metal organic viper phase epitaxy (MOVPE) at a substrate temperature of 750 °C. The Jth exhibits a unique non-monotonic behaviour as the temperature varies. Starting from 190 K, the threshold current density initially increases with temperature and reaches a local maximum at around 220 K. Beyond this point, Jth decreases, reaching a minimum at approximately 260 K, before increasing again in a superlinear manner at higher temperatures. Such anomalous temperature behaviour has also been previously observed in p-doped InAs/GaAs QD lasers, particularly under low-temperature conditions, suggesting similar underlying mechanisms.

Photoluminescence and spontaneous emission measurements reveal two emission peaks, indicating contributions from both quantum dot and quantum well (QW) states. This dual-state behaviour supports a model where carrier distribution between QD and QW states strongly influences Jth. Notably, this interpretation explains the observed characteristics without invoking Auger recombination, emphasizing the dominant role of carrier dynamics and thermal redistribution processes in determining laser efficiency and temperature sensitivity.

Prof. Al-Ghamdi completed his Ph.D degrees at Cardiff University UK in 2010. Afterword he got position at King Abdulaziz University in Saudi Arabia. Then he established the optoelectronic laboratory at King Abdulaziz University. He supervised more than 10 postgraduate students and recived more than 8 funded projects form outside and inside the university. Prof. Al-Ghamdi research interest includes the design and fabrication of semiconductor devices laser diode and studies the optoelectronic and electrical properties of these devices by measuring their absorption, spontaneous, stimulated emission spectra, ideality factor, barrier height and series resistance. The current research topics include red emitters quantum dot laser diode which used in photodynamic therapy for cancer treatment and also used in the manufacture of dual wavelength sources for data storage. Prof. Al- Ghamdi has over 65 publications that have been cited over 600 times, and his publication h-index is

14. He is a member of IEEE and OSA societies.