Synthesis, Phase Transformation And Photo-sensitivity Of In₂Se₃ Nanowires

Low-dimensional phase-change nanostructures provide a valuable scientific research platform for understanding the phase-transition behavior and material thermal properties at nanoscale, in addition to their potential to achieve super-dense data storage. One-dimensional phase-change nanowires have been investigated for the fabrication of electrically operated phase change random access memory (PRAM). Among them, In₂Se₃ nanowire is highly promising for applications in nonvolatile data storage since it exhibits high resistivity, a resistance switching ratio of 10⁵, and memory switching at much lower input power/energy than for GeTe and Ge₂Sb₂Te₅ nanowire devices. In addition, In₂Se₃ nanostructures have potential applications in solar cells, photosensors and lithium ion batteries.We report preparation ofα- andκ-phase In₂Se₃ nanowires by thermal evaporation and investigation of their phase transformations in-situ by synchrotron radiation X-ray diffraction (XRD) during a thermal annealing process. Theκ-phase transformed toα-phase at 500°C and eventually transformed to high temperatureα-phase with a layered structure of 5 atoms-5 atoms at 700°C irreversibly. Different atomistic structures of In₂Se₃ were modeled and optimized by DFT (Density Functional Theory) method, which correlates well with the synchrotron radiation XRD results. The In₂Se₃ nanowires also exhibit a large difference in resistivity before and after annealing. In addition,the photo sensitivity property of In₂Se₃ nanowires to visible and UV light is studied. The single In₂Se₃ nanowire prototyped device can detect the visible and UV light and the performance of the device is dependent on the wavelength of light, temperature and test voltage.