Threshold Temperature Dependence of a Quantum-Dot Laser Diode With and Without p-Doping

A study of the threshold characteristics of quantum-dot (QD) laser diodes shows how inhomogeneous broadening and p-doping influence the QD laser's temperature dependence of threshold
T

₀
. The analysis includes the additional parameters of homogeneous broadening, quantum state populations, and threshold gain. The results show that while the source of negative
T

₀
can occur due to different effects, the transparency current plays a critical role in both undoped and p-doped QD lasers. Experimental trends of negative
T

₀
and their dependence on p-doping are replicated in the calculated results. Inhomogeneous broadening is found to play a lesser role to the transparency current in setting
T

₀
. Homogeneous broadening is most important for uniform QDs with thermally isolated ground-state transitions.