Many sensing applications rely on light-matter interaction. Photonics components that emit and detect in the mid-infrared frequency range, also known as the molecular fingerprint region, are key to applications in environmental sensing, food monitoring and biomedical diagnostics. These photonics components are difficult and expensive to manufacture, as they are typically not compatible with conventional, low-cost complementary metal-oxide-semiconductor (CMOS) manufacturing processes.

The EU-funded LASTSTEP - group-IV LASer and deTectors on Si-TEchnology Platform project will overcome this problem using silicon-germanium-tin semiconductors that feature unique optical properties and compatibility with state-of-the-art CMOS manufacturing processes. This will lead to the world’s first monolithic all-Group-IV photonic platform, cost-effective and ready for widespread adoption, to be demonstrated in four prototypes for two use cases.

In detail, the Department of Electronics, Information and Bioengineering – Politecnico di Milano will contribute to the design and experimental characterization of GeSn based photodetectors. TCAD modelling will be used for device modelling and design. A supercontinuum laser and a FTIR set-up will be used for photoresponse measurements. Temperature dependent current-voltage and capacitance voltage measurements will be performed to highlight the physical mechanism behind the dark current generation of these new devices. We will also explore the possibility to operate such detectors in Geiger-mode for detecting single photons.