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Recent development on Ge1−xSnx nanowires with high Sn content, beyond its solid solubility limit, makes them attractive for all group-IV Si-integrated infrared photonics at the nanoscale. Herein, we report a chemical vapor deposition-grown high Sn-content Ge–Ge0.92Sn0.08 core–shell based single nanowire photodetector operating at the optical communication wavelength of 1.55 μm. The atomic concentration of Sn in nanowires has been studied using x-ray photoelectron and Raman spectroscopy data. A metal–semiconductor–metal based single nanowire photodetector, fabricated via an electron beam lithography process, exhibits significant room-temperature photoresponse even at zero bias. In addition to the high-crystalline quality and identical shell composition of the nanowire, the efficient collection of photogenerated carriers under an external electric field results in the superior responsivity and photoconductive gain as high as ∼70.8 A/W and ∼57, respectively, at an applied bias of −1.0 V. The extra-ordinary performance of the fabricated photodetector demonstrates the potential of GeSn nanowires for future Si CMOS compatible on-chip optical communication device applications. [ABSTRACT FROM AUTHOR]

A single step process to grow Au capped oxygen deficient GeO2 crystalline nanowires via generation of growth species through the metal induced surface decomposition of Ge substrate is reported. Without the external source supply, the growth of the Au-GeO2 nanowires on the Ge substrate is addressed with possible mechanism. Despite high band gap, application of GeO2 as a possible new material for visible light photodetection is presented. The as-grown samples were found to have a photo-response of ≥10² with 17% external quantum efficiency at -2.0 V applied bias upon visible-light illumination (λ = 540 nm, 0.2 mW/cm²). This visible-light detection can be attributed to the oxygen vacancy related defect states as well as localized surface plasmon resonance induced absorption and subsequent hot electron injection from Au to conduction band of GeO2. The photodetection performance of the devices has been understood by the proposed energy band diagrams. In addition, ≈4 times enhancement in the efficiency has been achieved by further decoration of the Au nanoparticles on the as-grown nanowire surfaces. [ABSTRACT FROM AUTHOR]