Local Heat Dissipation and Elasticity of Suspended Silicon Nanowires Revealed by Dual Scanning Electron and Thermal Microscopies

Abstract

A novel combined setup, with a scanning thermal microscope (SThM) embedded in a scanning electron microscope (SEM), is used to characterize a suspended silicon rough nanowire (NW), which is epitaxially clamped at both sides and therefore monolithically integrated in a microfabricated device. The rough nature of the NW surface, which prohibits vacuum‐SThM due to loose contact for heat dissipation, is circumvented by decorating the NW with periodic platinum dots. Reproducible approaches over these dots, enabled by the live feedback image provided by the SEM, yield a strong improvement in thermal contact resistance and a higher accuracy in its estimation. The results—thermal resistance at the tip‐sample contact of 188±3.7K µW−1 and thermal conductivity of the NW of 13.7±1.6W m−1 K−1—are obtained by performing a series of approach curves on the dots. Noteworthy, the technique allows measuring elastic properties at the same time—the moment of inertia of the NW is found to be (6.1±1.0) × 10−30m4—which permits to correlate the respective effects of the rough shell on heat dissipation and on the NW stiffness. The work highlights the capabilities of the dual SThM/SEM instrument, in particular the interest of systematic approach curves with well‐positioned and monitored tip motion.

Unraveling the Impact of Boron Nitride and Silicon Nitride Nanoparticles on Thermoplastic Polyurethane Fibers and Mats for Advanced Heat Management

“…This can lead to poor processability, inferior mechanical properties, and increased cost. Therefore, controlling the spatial arrangement and orientation of fillers are key parameters to design composites with high thermal conductivity at lower filler loadings. − Electrospinning offers a versatile and scalable approach for producing composite fibers, meshes, and yarns in a single step. − It enables the addition of fillers in high loading percentages and enhances the filler distribution with controllable orientation along the axial direction of polymer fibers. , Moreover, the synergy of the applied electrical field and fillers’ organization during electrospinning improves the alignment of the polymer molecule chains, thereby augmenting the intrinsic thermal conductivity and Young’s modulus of the polymer matrix. − This enhancement in properties expands their applications in yarns, textiles, aerospace engineering, and biomedical devices. − Therefore, understanding the thermal properties of individual micro- and nanofibers is crucial for optimizing material performance and functionality, especially given the unique characteristics that emerge in low-dimensional nanostructures, such as size and temperature dependence of thermal conductivity, and internal phonon boundary and edge scatterings. , Scanning thermal microscopy (SThM) with excellent spatial resolution (<50 nm) and thermal sensitivity (<0.01 °C) stands out among methods for characterizing thermal properties, including materials’ thermal conductivity at the micro- and nanoscale. In this technique, a heated nanothermal tip contacts and scans the surface of the samples at room temperature, capturing and processing thermal feedback signals to derive local temperature distribution on the samples. − …”