Enhanced temperature stability of threshold current of InAs/GaAs quantum dot lasers by AlGaAs lateral potential barrier layers

Abstract

We have investigated the incorporation of an AlGaAs lateral potential barrier layer (LPBL) as a novel approach to improve the temperature stability of the threshold current in InAs/GaAs quantum dot (QD) lasers. This layer serves to increase the energy separation (ΔE) between the ground and excited states of the QD while maintaining efficient vertical carrier injection. Theoretical calculations confirm that the LPBL is effective in increasing ΔE. The LPBLs were successfully formed using the preferential growth properties of AlGaAs induced by the non-uniform distribution of strain effects on the QD surface during molecular beam epitaxy growth. To confirm the usefulness of the LPBLs, we fabricated an InAs/GaAs QD laser incorporating AlGaAs LPBLs, demonstrating that the threshold current at 150°C was significantly reduced by 48% compared to a QD laser without LPBLs. The temperature stabilization achieved by incorporating the LPBLs provides a promising way for establishing high reliability and low power operation of QD lasers in high-temperature environments.