Extended-SWIR Photodetection in All-Group IV Core/Shell Nanowires

Group IV Ge 1– x Sn x semiconductors hold the premise of enabling broadband silicon-integrated infrared optoelectronics due to their tunable band gap energy and directness. Herein, we exploit these attributes along with the enhanced lattice strain relaxation in Ge/Ge 0.92 Sn 0.08 core/shell nanowire heterostructures to implement highly responsive room-temperature short-wave infrared nanoscale photodetectors. Atomic-level studies confirm the uniform shell composition and its higher crystallinity with respect to thin films counterparts. The demonstrated Ge/Ge 0.92 Sn 0.08 p-type field-effect nanowire transistors exhibit superior optoelectronic properties achieving simultaneously relatively high mobility, high ON/OFF ratio, and high responsivity, in addition to a broadband absorption in the short-wave infrared range. Indeed, the reduced band gap of the Ge 0.92 Sn 0.08 shell yields an extended cutoff wavelength of 2.1 μm, with a room-temperature responsivity reaching 2.7 A/W at 1550 nm. These results highlight the potential of Ge/Ge 1– x Sn x core/shell nanowires as silicon-compatible building blocks for nanoscale-integrated infrared photonics.