The photoconductive characteristics of CdS single nanoribbons were investigated. The device characteristics, including spectral response, light intensity response, and time response, were studied systematically. It is found that CdS nanoribbon has the response speed substantively faster than those ever reported for conventional film and bulk CdS materials and the size of nanoribbons has a significant influence on the response speed with smaller CdS nanoribbons showing higher response speed. The high photosensitivity and high photoresponse speed are attributable to the large surface-to-volume ratio and high single-crystal quality of CdS nanoribbons and the reduction of recombination barrier in nanostructures. Measurements in a different atmosphere demonstrate that the absorption of ambient gas (mainly oxygen) can significantly change the photosensitivity of CdS nanoribbons through trapping electrons from the nanoribbons.

As an interesting layered material, molybdenum disulfi de (MoS 2 ) has been extensively studied in recent years due to its exciting properties. However, the applications of MoS 2 in optoelectronic devices are impeded by the lack of high-quality p-n junction, low light absorption for mono-/multilayers, and the diffi culty for large-scale monolayer growth. Here, it is demonstrated that MoS 2 fi lms with vertically standing layered structure can be deposited on silicon substrate with a scalable sputtering method, forming the heterojunctiontype photodetectors. Molecular layers of the MoS 2 fi lms are perpendicular to the substrate, offering high-speed paths for the separation and transportation of photo-generated carriers. Owing to the strong light absorption of the relatively thick MoS 2 fi lm and the unique vertically standing layered structure,

A facile fabricating method has been established for large-area uniform silicon nanowires arrays. All silicon nanowires obtained were single crystals and epitaxial on the substrate. Six kinds of silicon wafers with different types, surface orientations, and doping levels were utilized as starting materials. With the catalysis of silver nanoparticles, room-temperature mild chemical etching was conducted in aqueous solution of hydrofluoric acid (HF) and hydrogen peroxide (H2O2). The corresponding silicon nanowires arrays with different morphologies were obtained. The silicon nanowires possess the same type and same doping level of the starting wafer. All nanowires on the substrate have the same orientation. For instance, both (100)- and (111)-oriented p-type wafers produced silicon nanowires in the (100) direction. For every kind of silicon wafer, the effect of etching conditions, such as components of etchant, temperature, and time, were systemically investigated. This is an appropriate method to produce a large amount of silicon nanowires with defined type, doping level, and growth direction for industrial applications.

A simple, low-cost blade-coating method is developed for the large-area fabrication of single-crystalline aligned CH3NH3PbI3 microwire (MW) arrays. The solution-coating method is applicable to flexible substrates, enabling the fabrication of MW-array-based photodetectors with excellent long-term stability, flexibility, and bending durability. Integrated devices from such photodetectors demonstrate high performance for high-resolution, flexible image sensors.

As an exotic state of quantum matter, topological insulators have promising applications in new-generation electronic and optoelectronic devices. The realization of these applications relies critically on the preparation and properties understanding of high-quality topological insulators, which however are mainly fabricated by high-cost methods like molecular beam epitaxy. We here report the successful preparation of high-quality topological insulator Bi2Se3/Si heterostructure having an atomically abrupt interface by van der Waals epitaxy growth of Bi2Se3 films on Si wafer. A simple, low-cost physical vapor deposition (PVD) method was employed to achieve the growth of the Bi2Se3 films. The Bi2Se3/Si heterostructure exhibited excellent diode characteristics with a pronounced photoresponse under light illumination. The built-in potential at the Bi2Se3/Si interface greatly facilitated the separation and transport of photogenerated carriers, enabling the photodetector to have a high light responsivity of 24.28 A W(-1), a high detectivity of 4.39 × 10(12) Jones (Jones = cm Hz(1/2) W(-1)), and a fast response speed of aproximately microseconds. These device parameters represent the highest values for topological insulator-based photodetectors. Additionally, the photodetector possessed broadband detection ranging from ultraviolet to optical telecommunication wavelengths. Given the simple device architecture and compatibility with silicon technology, the topological insulator Bi2Se3/Si heterostructure holds great promise for high-performance electronic and optoelectronic applications.