Geometry-Controlled Polarization Photocurrents in Scalable PtSe2 Infrared Pixels
Polarization-sensitive photodetectors provide multi-dimensional optical information beyond the capabilities of traditional intensity-based detectors. The noble metal dichalcogenide PtSe2 presents unique opportunities for tunable polarization detection due to its strong spin-orbit coupling, material stability, customizable broadband polarization responses, and direct compatibility with a wide range of substrates for back-end-of-line silicon integration. In this work, we demonstrate room-temperature near-infrared to mid-wavelength infrared polarization photoresponses using scalable, as-grown, wide-area PtSe2 films, and we show that the measured polarization response is reshaped by device geometry. Finite-element current-flow simulations reproduce the observed spatial redistribution of the polarization-sensitive response and localize the transverse polarization response near the pixel center. This geometry-enabled separation allows wavelength-dependent laser spot scans to distinguish symmetry-allowed photocurrents from contact-proximate, dichroism-mediated photothermal contributions. At near-infrared wavelengths, we observe spatial response that is consistent with linear-dichroic photothermoelectric currents, whereas mid-wavelength infrared measurements reveal a helicity-dependent photothermal contribution under oblique illumination. These results identify pixel boundary engineering as both a design lever and a diagnostic tool for scalable PtSe2 polarization-sensitive infrared pixels.