Supercritical fluid-enhanced IFVD quantum well intermixing for the regrowth-free photonic integration of EAM and SOA

In this study, we propose and demonstrate the enhancement of impurity-free vacancy diffusion (IFVD) quantum well intermixing (QWI) using supercritical fluid (SCF) treatment for photonic integration. Using an InGaAsP-based multiple quantum well (MQW) template for local bandgap engineering, SCF CO2 with H2O2 on a patterned SiOx capping layer could lower the QWI temperature to get a constant wavelength blueshift. Higher oxygen concentration was found in SiOx through high diffusivities and pressures of SCF and dehydration, enabling highly activated Ga2O3 reactions for more vacancies. Additionally, different schemes of semiconductor optical amplifier (SOA)-integrated electroabsorption modulators (EAM) were fabricated. SCF treatment could realize a 9- and 6-dB improvement in extinction ratio and gain, respectively, and then high-speed 45Gb/s modulation, greatly reducing the common issue of p-type dopant (zinc) diffusion during QWI.