Enhancing device characteristics of 1.3 μm emitting InAs/GaAs quantum dot lasers through dot-height uniformity study

• Realization of 1.3 μm emitting InAs/GaAs quantum dot laser on GaAs substrate.
• QD lasers with uniform dot height show low threshold current density.
• Improving the internal quantum efficiency of a dot laser by dot-height uniformity study.
• Theoretical calculation correlates well with the experimental results.

This study systematically improves the dot-height uniformity of InAs/GaAs quantum dot (QD) active layer grown by molecular beam epitaxy system in 1.3 μm-emitting QD laser diodes. The resulting self-assembled QDs with improved uniformity exhibited an elongated emission wavelength and a reduced linewidth of QD photoluminescence (PL) spectra. The 1.3 μm-emitting QD lasers with an as-cleaved 5-μm ridge fabricated under optimal growth conditions exhibited a low threshold current density of 250 A/cm2 and a high internal quantum efficiency of 63% under continuous-wave operation. The photoluminescent properties and characteristics of the 1.3 μm-emitting QD lasers was also investigated theoretically using an effective mass model and correlated well with the experimental results, which elucidative clarifying the significant role of dot-height uniformity in achieving high performance QD lasers.