InAs quantum dots with a narrow photoluminescence linewidth for a lower threshold current density in 1.55 µm lasers

Abstract

Uniform quantum dots (QDs) with a narrowed linewidth of photoluminescence (PL) are crucial for developing high-performance QD lasers. This study focuses on optimizing the growth conditions of InAs QDs on (001) InP substrates using metal-organic chemical vapor deposition (MOCVD), targeting applications in 1.55 µm QD lasers. By fine-tuning growth parameters such as the V/III ratio, deposition thickness, and growth temperature, we attained a QD density of 4.13 × 1010 cm−2. Further, a narrowed PL full width at half maximum (FWHM) of 40.1 meV was achieved in a five-stack InAs QD layer. This was accomplished using the double-cap technique, which reduced the height dispersion of QDs and shifted the emission wavelength to 1577 nm. Broad-area lasers incorporating a five-stack optimized InAs/InAlGaAs structure demonstrated a low threshold current density of 80 A/cm2 per QD layer, and a saturation power of 163 mW in continuous-wave (CW) mode at room temperature.