Subthreshold diode characteristics of InAs/GaAs quantum dot lasers

The temperature dependence of the carrier dynamics in ensembles of InAs/GaAs quantum dots (QDs) are of interest, both from a fundamental point of view but also because of the consequences for the performance of QD-based optoelectronic devices. While this topic has been studied before using optical techniques, here we approach the topic by analyzing the current-voltage (I-V) characteristic of QD diodes. Using a current-modulation technique, the transition from “traplike” to “thermalized” behavior as the temperature is raised from 80 K to room temperature is observed. Furthermore, the results suggest that the I-V curve is sensitive to the separate escape of electrons and holes, and the intersubband spacing of the electron states and that of the hole states is estimated from the data.