High Absorption Contrast Quantum Confined Stark Effect in Ultra-Thin Ge/SiGe Quantum Well Stacks Grown on Si

We report on the performance of the quantum confined Stark effect (QCSE) in ultra-thin (similar to 350 nm) Ge/SiGe quantum well stacks grown on Si. We demonstrate an absorption contrast Delta alpha/alpha of 2.1 at 1 Vpp swing in QCSE stacks grown on ultra-thin (100 nm) strain relaxed GeSi buffer layers on 300 mm Si wafers. Such ultra-thin QCSE stacks will enable future integration of highly efficient QCSE electro-absorption modulators with low optical coupling loss to passive Si waveguides in a sub-micron silicon photonics platform.