Abstract
The light sensitivity of a novel TiO2/TiN-nanotubes-based photodetector is improved by coating it with Au nanoparticles. Using a porous aluminum oxide template (PAOT), TiO2/TiN nanotubes were produced. A two-step anodization procedure was used to produce the PAOT using the Ni-imprinting method. Atomic layer deposition and magnetron sputtering were used to deposit the TiO2/TiN layers. X-ray diffraction, scanning electron mi-croscopy, and reflection/absorption optical spectroscopy were used to characterize the PAOT, PAOT/TiO2/TiN, and PAOT/TiO2/TiN/Au. With a pore diameter of 320 nm and an interpore distance of 61 nm, the PAOT exhibits a high-ordered hexagonal nanoporous array. Following the deposition of TiN on the PAOT/TiO2, the bandgap of PAOT/TiO2 reduced from 3.1 to 2.2 eV, indicating increased visible light absorption. The photoresponsivity values for PAOT/TiO2/TiN and PAOT/TiO2/TiN/Au photodetectors are almost the same (453 mA W-1) at 390 nm. Without and with Au coating, the photoresponsivity values at 636 nm are 392 and 438 mA W 1, suggesting a considerable increase in the Vis/NIR range. Moreover, the detectivity values for the photodetector are enhanced after Au coating, in which the detectivity value for photodetectors are 8.74 x 10(9) and 8.75 x 10(12) Jones at 636 nm before and after Au coating, respectively. While the detectivity values are 8.86 x 10(12) Jones for both photodetectors at 390 nm. As a result of the hot electrons from the TiN and Au layers, the constructed photo-detector has a very high photoelectrical response, making it extremely promising as a broadband photodetector.