Zheng, BobZhao, HangqiCerjan, BenYazdi, SadeghRinge, EmilieNordlander, PeterHalas, Naomi J.2018-11-012018-11-012018Zheng, Bob, Zhao, Hangqi, Cerjan, Ben, et al.. "A room-temperature mid-infrared photodetector for on-chip molecular vibrational spectroscopy." <i>Applied Physics Letters,</i> 113, no. 10 (2018) AIP Publishing: https://doi.org/10.1063/1.5045663.https://hdl.handle.net/1911/103287Infrared (IR) photodetection is of major scientific and technical interest since virtually all molecules exhibit characteristic vibrational modes in the mid-infrared region of the spectrum, giving rise to molecular spectroscopy and chemical imaging in this wavelength range. High-resolution IR spectroscopies, such as Fourier Transform IR spectroscopy, typically require large, bulky optical measurement systems and expensive photodetector components. Here, we present a high-responsivity photodetector for the mid-IR spectral region which operates at room temperature. Fabricated from silicon and aluminum, the photodetection mechanism is based on free carrier absorption, giving rise to a photoresponse rivalling commercially available cooled IR photodetectors. We demonstrate that infrared spectra of molecules deposited on this detector can be obtained by a direct electrical read-out. This work could pave the way for simple, fully integrated chemical sensors and other applications, such as chemical imaging, which would benefit from the combination of mid-IR detection, room-temperature operation, and ultracompact portability.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttps://doi.org/10.1063/1.5045663