Tunable SWIRAbsorption Peaks in GeSn Nanowire ArrayPhotodetectors

Monolithic infrared imaging, sensing, and data communication technologies are being developed using direct band gap GeSn semiconductors grown on a Si wafer. Here, we present a room-temperature Ge0.92Sn0.08 photodetector where the epilayer is shaped into an array of nanowires (NWs) to boost optical absorption and enrich device functionality in the short-wave infrared (SWIR). Leaky-mode resonance (LMR) peaks in the untapered NW array result in a 4-fold increase in the SWIR absorption compared to the as-grown sample. The position of the LMR peaks is precisely controlled from 1.1 μm up to the 2.6 μm cutoff wavelength by carefully tuning the nanowire diameter from 200 to 1050 nm. The NW array photodetector operates at room-temperature with increased responsivity compared to the planar mesa device, and with a peak detectivity D* = 5.4·107 cm·Hz1/2W–1 at 2.0 μm. This nanostructuring approach will unlock longer infrared wavelengths by increasing the Sn content in the GeSn heterostructure, enabling the design of novel uncooled, multispectral infrared sensing and imaging systems.