2023/11/30 by Lu Luo, Luo, Lu, Mahmoud R. M. Atalla +7 · 1 citation
Engineering · Physics and Astronomy · #FOS: Physical sciences #Mechanical and Optical Resonators #Nanowire Synthesis and Applications #Optics (physics.optics) #Photonic and Optical Devices
paper · pdf · doi:10.48550/arxiv.2311.18569
openalex publication_date 2023/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Achieving high crystalline quality Ge1-xSnx semiconductors at Sn content exceeding 10% is quintessential to implementing the long sought-after silicon-compatible mid-infrared photonics. Herein, by using sub-20 nm Ge nanowires as compliant growth substrates, Ge1-xSnx alloys with a Sn content of 18% exhibiting a high composition uniformity and crystallinity along a few micrometers in the nanowire growth direction were demonstrated. The measured bandgap energy of the obtained Ge/Ge0.82Sn0.18 core/shell nanowires is 0.322 eV enabling the mid-infrared photodetection with a cutoff wavelength of 3.9 μm. These narrow bandgap nanowires were also integrated into top-gated field-effect transistors and phototransistors. Depending on the gate design, these demonstrated transistors were found to exhibit either ambipolar or unipolar behavior with a subthreshold swing as low as 228 mV/decade measured at 85 K. Moreover, varying the top gate voltage from -1 V to 5 V yields nearly one order of magnitude increase in the photocurrent generated by the nanowire phototransistor under a 2330 nm illumination. This study shows that the core/shell nanowire architecture with a super thin core not only mitigates the challenges associated with strain buildup observed in thin films but also provides a promising platform for all-group IV mid-infrared photonics and nanoelectronics paving the way toward sensing and imaging applications.