Continuous-wave electrically pumped 1550  nm lasers epitaxially grown on on-axis (001) silicon

Abstract

Heteroepitaxy of III–V compound semiconductors on industry standard (001) silicon (Si) substrates is highly desirable for large-scale electronic and photonic integrated circuits. Challenges of this approach relate primarily to lattice, polarity, and coefficient of thermal expansion mismatch, which ultimately generate a high density of defects and limit the reliability of active devices. Ongoing efforts to monolithically integrate lasers in silicon photonics include leveraging quantum dots for reduced sensitivity to defects and the ability to enable 1310 nm lasers with gallium arsenide (GaAs) and related compounds. In this work, to extend the operation window to the widely used 1550 nm telecommunications region, we have demonstrated continuous-wave (CW) electrically pumped indium phosphide (InP)-based quantum well lasers on complementary metal-oxide-semiconductor (CMOS)-compatible (001) Si. Heteroepitaxy of InP and related compounds on Si poses additional challenges because the lattice mismatch is significantly larger compared to GaAs. Key to our approach is the development of a low dislocation density InP-on-Si template by metalorganic chemical vapor deposition (MOCVD). Following an InP buffer with a surface defect density of ${1.15} \times {{10}^8}/{{\rm cm}^2}$1.15×108/cm2, a seven-layer indium gallium arsenide phosphide (InGaAsP) multi-quantum well laser diode structure was grown. Fabry–Perot ridge waveguide lasers were then fabricated. A 20-µm wide and 1000-µm long laser demonstrates a room temperature continuous-wave (CW) lasing threshold current density of ${2.05}\;{{\rm kA}/{\rm cm}^2}$2.05kA/cm2 and a maximum output power of 18 mW per facet without facet coating. CW lasing up to 65°C and pulsed lasing greater than 105°C were achieved. This MOCVD-based heteroepitaxy approach offers a practical path toward monolithic integration of InP lasers in silicon photonics.