GeSn/Ge/Si Detector to Extend SWIR Sensor Sensitivity to 2.45um

Photonics: Researchers at the Forschungszentrum Jülich (Jülich Research Center) and the Politecnico di Milano (Polytechnic University of Milan) have developed an IR detector that provides a bias-switchable spectral response in two distinct IR bands. When the bias voltage for the detector is reversed, the device switches from the NIR to the SWIR band. The dual-band photodetector is Si-wafer based and is said to be suitable for integration into cameras and smartphones.

The paper "CMOS-Compatible Bias-Tunable Dual-Band Detector Based on GeSn/Ge/Si Coupled Photodiodes" by Enrico Talamas Simola, Vivien Kiyek, Andrea Ballabio, Viktoria Schlykow, Jacopo Frigerio, Carlo Zucchetti, Andrea De Iacovo, Lorenzo Colace, Yuji Yamamoto, Giovanni Capellini, Detlev Grützmacher, Dan Buca, and Giovanni Isella is published in ACS Photonics.

"Here, we present a two-terminal dual-band detector, which provides a bias-switchable spectral response in two distinct IR bands. The device is obtained from a vertical GeSn/Ge/Si stack, forming a double junction n-i-p-i-n structure, epitaxially grown on a Si wafer. The photoresponse can be switched by inverting the bias polarity between the near and the short-wave IR bands, with specific detectivities of 1.9 × 1010 and 4.0 × 109 cm·(Hz)1/2/W, respectively. The possibility of detecting two spectral bands with the same pixel opens up interesting applications in the field of IR imaging and material recognition, as shown in a solvent detection test. The continuous voltage tuning, combined with the nonlinear photoresponse of the detector, enables a novel approach to spectral analysis, demonstrated by identifying the wavelength of a monochromatic beam."