germanium Quantum wells for SENSing in the mid-infrarEd

In the last years, photonics integrated circuits (PICs)operating in the Mid-infrared (MIR), where molecules display their unique spectral fingerprints,have been proposed for applications in the field of medical diagnostics, analytical chemistry, environmental monitoring, and sensing for safety and security. In this context, the present project proposal targets the demonstration of novel architectures for PIC sensing chips operating in the MIR, fabricated from SiGe layers epitaxially grown on a Si wafer.The final goal is the demonstration of a sensing platform for the detection of the spectral fingerprint of a large class of analytes. Beside their well-known compatibility with the mainstream silicon photonics technology, Ge-rich SiGe epitaxial layers feature an high transparency in the MIR up to λ = 15 μm. This important feature, combined with the higher refractive index of SiGe with respect to Si, makes this material platform uniquely well suited to design and fabricate broad-band, low-loss MIR waveguides (WG). Most importantly, the epitaxial SiGe system can host heterostructures with potential barriers to form quantum wells, which can be used to design integrated photodetectors. The chips developed in this project will thenhost waveguideswith an optical sensing region, where the analytes will interact with the evanescent filed of the guided mode, and an integrated quantum well infrared photodetector (QWIP).