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Manipulation of electron beam irradiation using TEM determines the selective region with a particular size and depth to conduct the subsequent process for nanopore formation. • Recording the effect of e-beam irradiation on Mo 5 O 14 nanowires by in situ TEM. • Manipulating e-beam to define the anticipated region and the size of nanoporosity. • Atom removal and crystallinity degradation resulting in structural transformation. • The formation of nanopores due to the numerous broken bonds in crystalline Mo 5 O 14. • Revealing the mechanism of selective nanopore formation in nanoscale modification. The Mo 5 O 14 -type structure is representative of the MoO-based catalyst in the selective oxidation process. Single-crystalline Mo 5 O 14 nanowires can be synthesized in a controlled manner by chemical vapor deposition (CVD). A nanowire catalyst with a porous structure combines the advantages of both nanoparticles and nanowires, leading to a substantial increase in the specific surface area. Therefore, we aim to manipulate the e-beam irradiation process on Mo 5 O 14 nanowires to induce the nanoporous structures in selected regions. In situ transmission electron microscopy (TEM) enabled us to visualize the structural transformation through gradual e-beam irradiation. The e-beam irradiation process removes oxygen atoms and renders the internal structure unstable. After the irradiated region is exposed to air, atoms tend to escape to decrease the internal energy. This results in the formation of nanopores because of the irradiation effect. By nanoscale modification method, the irradiated region is controlled by the electron beam size, which determines the nanopore distribution in the selected region. The study is beneficial for increasing the surface area of Mo 5 O 14 -type catalysts with variable nanopore densities and for modifying nanomaterials using a convenient method. [ABSTRACT FROM AUTHOR]

The atomic scale Silicidation of Ni-Si System by In-situ TEM Investigation could be divide into three steps. At the first step (250 °C), Ni would diffuse into Si substrate to synthesize triangular Ni 2 Si. Afterwards, continuous NiSi thin films would be synthesized at 400 °C. At last, trapezoid NiSi would react with Si to form NiSi 2 at third step (600 °C). Furthermore, the electric electrical properties of Ni-Si system were identified by four-point probe measurements; the resistivities of NiSi, Ni 2 Si and NiSi 2 were 14.13 µΩ∙cm, 22.80 µΩ∙cm and 37.77 µΩ∙cm, respectively. • The diffusion behaviour of Ni-Si system was investigated through in situ HRTEM. • Ni 2 Si and NiSi were diffusion controlled and NiSi 2 was nucleation controlled. • The resistivities of NiSi, Ni 2 Si and NiSi 2 were 14.1, 22.8, and 37.7 µΩ∙cm, respectively. • The diffusion rate could be calculated by in-situ TEM observation. • This work provides a novel method to obtain low resistivity silicide for IC devices. Nickel silicide has many advantages, such as low resistivity and low formation temperature; therefore, it has been widely used in the fields of solar cells, transistors and complementary metal-oxidesemiconductor (CMOS) devices. To obtain high-quality nickel-silicide thin film, solid-state reaction is a convenient and efficient fabrication method. For better understanding of the dynamic formation mechanism, we used in-situ transmission electron microscopy (TEM) to record the diffusion behavior during the heating process. In this work, three-steps annealing process to synthesize different nickel silicides corresponding to the various formation temperatures were investigated systematically. At 250 °C, the product of the first-step annealing was inverted-triangle Ni 2 Si, embedded in the Si substrate. Then, well-distributed NiSi thin film was synthesized, having the lowest resistivity among Ni-Si system at 400 °C. Finally, NiSi 2 , a Si-rich product, would form during the third-step annealing at 600 °C. NiSi 2 product and Si substrate have small lattice mismatch; thus, the epitaxial relationship would be observed. We provide the evidence of diffusion behaviors and structural identification of Ni-Si system. Furthermore, these results are beneficial for the formation of specific nickel silicides, which is expected to optimize the fabrication of microelectronics. [ABSTRACT FROM AUTHOR]