Recently, ultraviolet (UV) photodetectors based on TiO2 semiconductors have attracted intensive attention, due to their wide applications in environmental and biological research, optical communication, astronomical investigations and missile launch detection. However, there still remain material-and fabrication-related obstacles in realizing highly efficient UV photodetectors. Here, we reported the exploration of the efficient UV photodetectors based on the highly ordered TiO2 nanotube arrays (TNAs). The TNAs were prepared by a two-step anodic oxidation with tailored tube lengths and wall thicknesses, and then transplanted to a transparent FTO substrate to construct a front-illuminated photodetector. The as-assembled photodetectors exhibit a satisfied stability and wavelength selectivity with a high photocurrent, photo-to-dark current ratio and responsivity up to 1395 A, 10730 and 176.3 AW -1 under the UV illumination of 350 nm (45 μWcm -1 ) at a given bias of 2 V with TiO2 tube length of 14.7μm, respectively, suggesting their promising applications in efficient UV photodetectors.  Corresponding authors;

High-performance solar-blind UV (ultraviolet) photodetectors (PDs) based on low-dimension semiconducting nanostructures with high sensitivity, excellent cycle stability, and the ability to operate in harsh environments are critical for solar observations, space communication, UV astronomy, and missile tracking. In this study, TiO 2 -ZnTiO 3 heterojunction nanowire-based PDs are successfully developed and used to detect solar-blind UV light. A photoconductive analysis indicates that the fabricated PDs are sensitive to UV illumination, with high sensitivity, good stability, and high reproducibility. Further analysis indicates that the rich existence of grain boundaries within the TiO 2 -ZnTiO 3 nanowire can greatly decrease the dark current and recombination of the electron-hole pairs and thereby significantly increase the device's photosensitivity, spectra responsivity (1.1 × 10 6 ), and external quantum efficiency (4.3 × 10 8 %). Moreover, the PDs exhibit good photodetective performance with fast photoresponse and recovery and excellent thermal stability at temperatures as high as 175 °C . According to these results, TiO 2 -ZnTiO 3 heterojunction nanowires exhibit great potential for applications in high-performance optical electronics and PDs, particularly next-generation photodetectors with the ability to operate in harsh environments.

Indium tin oxide (ITO)-based sandwich structures with the insertion of ultrathin (<10 nm) titanium nitride (TiN) are investigated as near-infrared (NIR) plasmonic materials. The structural, electrical, and optical properties reveal the improvement of the sandwich structures stemmed from TiN insertion. TiN is a well-established alternative to noble metals such as gold, elevating the electron conductivity of sandwich structures as its thickness increases. Dielectric permittivities of TiN and top ITO layers show TiN-thickness-dependent properties, which lead to moderate and tunable effective permittivities for the sandwiches. The surface plasmon polaritons (SPP) of the ITO-TiN-ITO sandwich at the telecommunication window (1480-1570 nm) are activated by prism coupling using Kretschmann configuration. Compared with pure ITO films or sandwiches with metal insertion, the reflectivity dip for sandwiches with TiN is relatively deeper and wider, indicating the enhanced coupling ability in plasmonic materials for telecommunications. The SPP spatial profile, penetration depth, and degree of confinement, as well as the quality factors, demonstrate the applicability of such sandwiches for NIR plasmonic materials in various devices.

In this work, phase change chalcogenide Ge 2 Sb 2 Te 5 (GST) thin films were fabricated by magnetron sputtering. The optical properties, especially the optical constants (refractive index and extinction coefficient), of such alloys were systematically studied by investigating their thermally and photo-