2021, Talamas Simola, Enrico, Kiyek, Vivien, Ballabio, Andrea, Schlykow, Viktoria, Frigerio, Jacopo, Zucchetti, Carlo, De Iacovo, Andrea, Colace, Lorenzo, Yamamoto, Yuji, Capellini, Giovanni, Grützmacher, Detlev, Buca, Dan, Isella, Giovanni

Infrared (IR) multispectral detection is attracting increasing interest with the rising demand for high spectral sensitivity, room temperature operation, CMOS-compatible devices. 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. © 2021 The Authors. Published by American Chemical Society.