Amorphous SiO2 (a-SiO2) thin films are widely used in integrated circuits (ICs) due to their excellent thermal stability and insulation properties. In this paper, the thermal conductivity of a-SiO2 thin film was systematically investigated using non-equilibrium molecular dynamics (NEMD) simulations. In addition to the size effect and the temperature effect for thermal conductivity of a-SiO2 thin films, the effect of defects induced thermal conductivity tuning was also examined. It was found that the thermal conductivity of a-SiO2 thin films is insensitive to the temperature from −55 °C to 150 °C. Nevertheless, in the range of the thickness in this work, the thermal conductivity of the crystalline SiO2 (c-SiO2) thin films conforms to the T−α with the exponent range from −0.12 to −0.37, and the thinner films are less sensitive to temperature. Meanwhile, the thermal conductivity of a-SiO2 with thickness beyond 4.26 nm has no significant size effect, which is consistent with the experimental results. Compared with c-SiO2 thin film, the thermal conductivity of a-SiO2 is less sensitive to defects. Particularly, the effect of spherical void defects on the thermal conductivity of a-SiO2 is followed by Coherent Potential model, which is helpful for the design of low-K material based porous a-SiO2 thin film in microelectronics.

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Ultraviolet (UV) photonics-based device and equipment have various applications in sterilization, military covert communication, medical treatment, nanofabrication, gem identification and so on. The traditional constituent UV components are bulky, inefficient, expensive and easily aging under UV radiation. An all-dielectric metasurface offers a promising way to control the amplitude, polarization and phase of light by engineering the size, shape and distribution of its constituent elements. However, UV components based on all-dielectric metasurfaces are difficult to be realized, due to significant absorption loss for most dielectric materials at the UV region. Here we demonstrate the design of a UV metalens, composed of high-aspect-ratio aluminum nitride nanorods. The in-plane on-axis, off-axis and out-of-plane focusing characteristics have been investigated at representative UVA (375 nm), UVB (308 nm) and UVC (244 nm) wavelengths, respectively. Furthermore, we design UV router for mono-wavelength and multiple wavelengths, that is, guiding UV light to designated different spatial positions. Our work is promising for the development of UV photonic devices and would facilitate the integration and miniaturization of the UV nanophotonics.

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