Electro-refractive effect in Ge/SiGe multiple quantum wells.

We report on the electro-refractive effect in Ge/SiGe multiple quantum wells grown by low energy plasma enhanced chemical vapor deposition. The electro-refractive effect was experimentally characterized by the shift of Fabry-Perot fringes in the transmission spectra of a 64 μm long slab waveguide. A refractive index variation up to 1.3 × 10-3 was measured with an applied electric field of 88 kV/cm at 1475 nm, 50 meV below the excitonic resonance, with a VπLπ figure of merit of 0.46 V cm. The device performances are promising for the realization of Mach Zehnder modulators in the Ge-Si material platform. [ABSTRACT FROM AUTHOR]