Abstract: Ge/Si core-shell nanowires (CSNWs) are regarded as strong candidates for next-generation electronic and optoelectronic devices, as they have a structure in which the carrier transport region is isolated from the impurity-doped region by hole gas that has accumulated between the interfaces. In this study, vertically-aligned i-Ge/p-Si CSNWs with different diameters were successfully fabricated using the top-down method, employing electron beam lithography (EBL) combined with chemical vapor deposition (CVD). Raman analysis exhibits hole gas accumulation that is clearly controllable by adjusting the size of the Ge core. A high-performance short-wave infrared (SWIR) photodetector was fabricated using i-Ge/p-Si CSNWs. Even without applied bias voltage, maximum responsivity reached 2.78 A/W under illumination with 1200 nm (near infrared) light. Maximum responsivity reached 16.57 A/W by controlling the hole gas concentration. Our results confirm that hole gas accumulation in i-Ge/p-Si CSNWs enables the fabrication of high-performance SWIR photodetectors.

Key words: Ge/Si core-shell nanowire arrays, Hole gas accumulation, Top-down fabrication, SWIR photodetector