Electron irradiation induced amorphous SiO2 formation at metal oxide/Si interface at room temperature; electron beam writing on interfaces

Molybdenum Disulfide-Assisted Spontaneous Formation of Multistacked Gold Nanoparticles for Deep Learning-Integrated Surface-Enhanced Raman Scattering

Several fabrication methods have been developed for label-free detection in various fields. However, fabricating high-density and highly ordered nanoscale architectures by using soluble processes remains a challenge. Herein, we report a biosensing platform that integrates deep learning with surface-enhanced Raman scattering (SERS), featuring large-area, close-packed three-dimensional (3D) architectures of molybdenum disulfide (MoS2)-assisted gold nanoparticles (AuNPs) for the on-site screening of coronavirus disease (COVID-19) using human tears. Some AuNPs are spontaneously synthesized without a reducing agent because the electrons induced on the semiconductor surface reduce gold ions when the Fermi level of MoS2 and the gold electrolyte reach equilibrium. With the addition of polyvinylpyrrolidone, a two-dimensional large-area MoS2 layer assisted in the formation of close-packed 3D multistacked AuNP structures, resembling electroless plating. This platform, with a convolutional neural network-based deep learning model, achieved outstanding SERS performance at subterascale levels despite the microlevel irradiation power and millisecond-level acquisition time and accurately assessed susceptibility to COVID-19. These results suggest that our platform has the potential for rapid, low-damage, and high-throughput label-free detection of exceedingly low analyte concentrations.

Electron and Neutron Beam Irradiation Effects in Homogeneous and Nanostructured Oxides

Oxide-based materials have a variety of applications in chemical sensing and photocatalysis, thin-film transistors, complex-oxide field-effect transistors, nonvolatile memories, resistive switching, energy conversion, topological oxide electronics, and many others. The radiation resistance of these materials in such devices plays an important role in device operation in radiation environment, and this attracts much attention in the research area. In spite of damage in a number of cases high-energy particles may have a beneficial effect on the target. In this mini-review article examples of both creation of defects and beneficial changes in the structure and properties of homogeneous and nanostructured oxides caused by high-energy electron and neutron irradiation are given by considering some recently published results. First, the attention is turned to ionizing and displacement effects of electron and neutron irradiation in homogeneous bulk and thin-film oxides reported in the literature. Then, the effect of electron and neutron irradiation on nanostructured oxides and semiconductor nanoparticles embedded in an oxide matrix is regarded. Considerable attention is paid to silicon oxide layers since they are widely used in microelectronic products, which are among the most manufactured devices in human history. Processes of irradiation-induced lattice rearrangement, compositional changes, growth of nanoparticles and their size reduction, creation of point defects and their complexes, electron-hole generation, and charge trapping are discussed.

Interface induced diffusion

Interface induced diffusion had been identified in a thin film system damaged by electron bombardment. This new phenomenon was observed in Al₂O₃ (some nm thick)/Si substrate system, which was subjected to low energy (5 keV) electron bombardment producing defects in the Al₂O₃ layer. The defects produced partially relaxed. The rate of relaxation is, however, was different in the vicinity of the interface and in the "bulk" parts of the Al₂O₃ layer. This difference creates an oxygen concentration gradient and consequently oxygen diffusion, resulting in an altered layer which grows from the Al₂O₃/Si substrate interface. The relative rate of the diffusion and relaxation is strongly temperature dependent, resulting in various altered layer compositions, SiO₂ (at room temperature), Al₂O₃ + AlO_x + Si (at 500 °C), Al₂O₃ + Si (at 700 °C), as the temperature during irradiation varies. Utilizing this finding it is possible to produce area selective interface patterning.