The practical realization of optoelectronic devices operating in the mid-infrared region is stimulated by both fundamental interests and applications ranging from spectroscopy, sensing, imaging, and security to communications. Despite significant achievements in semiconductors, essential barriers including the cryogenic operation and complicated growth processes prevent the applications of mid-infrared detectors. Graphene is widely used in modern electronics, but its low absorption limits photodetection. It is therefore of interest to extend the performance of graphene photodetectors into the mid-infrared region. Here, we first demonstrate pure graphene photodetectors operating in a broadband range from the deep ultraviolet to the mid-infrared region by utilizing photoionization of shallow impurities and over band gap excitation in highly doped Si:B and Si:P substrates. We have observed a photoresponsivity of ∼5 A/W under the mid-infrared illumination at room temperature. This approach paves the way for a concept of dual-photogating effect induced by both highly doped Si substrates and nanomaterials/nanostructures on top of graphene field-effect transistors.

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The fast degradation rate and poor wear resistance of magnesium (Mg) alloys in physiological environments have limited their potential usage as next-generation biodegradable orthopedic implant materials. In this work, femtosecond laser shock peening (fs-LSP) was successfully applied to simultaneously improve the surface mechanical, corrosion, and tribocorrosion properties of WE43 Mg alloys in blood bank buffered saline solution at body temperature. Specifically, the treated surfaces of WE43 Mg alloys via fs-LSP with ultralow pulse energy were investigated under different power densities, confining mediums, and absorbent materials. It was found that the combination of a black tape and a quartz layer gave the optimum peening effect under a power density of 28 GW/cm 2 , which simultaneously strengthened the surface and reduced the corrosion kinetics. In addition, a rapid self-repassivation was observed in fs-LSP-treated WE43 surfaces during tribocorrosion, promising sustained corrosion resistance under mechanical loading, critical to the reliability of load-bearing implants. Finally, the subsurface microstructural evolution and residual stress development in WE43 after fs-LSP were discussed based on the results from transmission electron microscopy analysis and finite element simulations.