Low-Defect Quantum Dot Lasers Directly Grown on Silicon Exhibiting Low Threshold Current and High Output Power at Elevated Temperatures

TL;DR

This paper presents a novel epitaxial growth method enabling high-performance InAs/GaAs-on-Silicon lasers with low threshold currents and high-temperature operation, comparable to native substrate lasers, advancing silicon photonics integration.

Contribution

Developed a new epitaxial approach that overcomes lattice mismatch issues, achieving high-quality III-V lasers directly on silicon with performance matching native substrates.

Findings

Achieved 6 mA threshold current in continuous-wave operation

Demonstrated high-temperature operation up to 165°C

Lasers on Si and GaAs show nearly identical threshold currents

Abstract

The direct growth of III-V materials on silicon is a key enabler for developing monolithically integrated lasers, offering substantial potential for ultra-dense photonic integration in vital communications and computing technologies. However, the III-V/Si lattice and thermal expansion mismatch pose significant hurdles, leading to defects that degrade lasing performance. This study overcomes this challenge, demonstrating InAs/GaAs-on-Si lasers that perform on par with top-tier lasers on native GaAs substrates. This is achieved through a newly developed epitaxial approach comprising a series of rigorously optimised growth strategies. Atomic-resolution scanning tunnelling microscopy and spectroscopy experiments reveal exceptional material quality in the active region, and elucidate the impact of each growth strategy on defect dynamics. The optimised III-V-on-silicon ridge-waveguide lasers demonstrate a continuous-wave threshold current as low as 6 mA and high-temperature operation reaching 165 {\deg}C. At 80 {\deg}C, critical for data centre applications, they maintain a 12-mA threshold and 35 mW output power. Furthermore, lasers fabricated on both Si and GaAs substrates using identical processes exhibit virtually identical average threshold current. By eliminating the performance limitations associated with the GaAs/Si mismatch, this study paves the way for robust and high-density integration of a broad spectrum of critical III-V photonic technologies into the silicon ecosystem.