InAs quantum dots with a narrow photoluminescence linewidth for a lower threshold current density in 1.55 µm lasers
Bin Wang, Xuezhe Yu, Yugang Zeng, Weijie Gao, Wei Chen, Haoyu Shen, Kedi Ma, Hongxiao Li, Zizhuo Liu, Hui Su, Li Qin, Yongqiang Ning, Lijun Wang
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 × 10 10 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/cm 2 per QD layer, and a saturation power of 163 mW in continuous-wave (CW) mode at room temperature.