SiGeSn material for integrated optical devices

In this paper, an ultra-thin buffer technology for the epitaxial growth of Si_xGe_1-x-ySn_y structures on Si or Si-on-Insulator substrates by using molecular beam epitaxy is presented. This technology builds the basis for integrated photonic devices as detectors, modulators and light sources. The paper discusses different device families with different material compositions, which all use a relaxed Ge virtual substrate with high quality. These are pseudomorphic Ge/Ge_1-ySn_y structures, Si_xGe_1-x-ySn_y structures lattice matched to Ge and (partially) relaxed Ge_1-ySn_y virtual substrates. The photonic devices consist of heterojunction diodes with vertical pin doping structures. As an example, Ge/Ge_1-ySn_y multi quantum well photodetectors which active regions made from Nx(Ge_0.93Sn_0.07/Ge) multi-quantum well structures are presented. Optical measurements at high frequencies are successfully performed on these photodetectors. A 3-dB bandwidth above 40 GHz is measured at the optical telecommunication wavelength of 1550 nm.