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In this study, we conducted calculations to determine the thermal conductivity of silicon nanowires with various shapes and cross-sectional designs using the Monte Carlo method combined with Green–Kubo heat flow autocorrelation. This computational approach is known for its reliability in predicting thermal properties of complex nanostructured devices. We specifically examined nanowires with circular or rectangular sections combined to complex serpentine and fishbone modulations. Our findings indicate that the nanowire's geometry significantly impacts the phonon mean free path and thermal transport. More specifically, patterns with serpentine modulations exhibit a pronounced reduction in thermal conductivity attributable to enhanced phonon boundary scatterings. Our simulation results are compared with the available experimental data, highlighting the potential of our method for structural optimization in thermal management applications, particularly in devices like thermoelectric converters. [ABSTRACT FROM AUTHOR]

Scanning Thermal Microscopy (SThM) has become an important measurement technique for characterizing the thermal properties of materials at the nanometer scale. This technique requires a SThM probe that combines an Atomic Force Microscopy (AFM) probe and a very sensitive resistive thermometer; the thermometer being located at the apex of the probe tip allows for the mapping of temperature or thermal properties of nanostructured materials with very high spatial resolution. The high interest of the SThM technique in the field of thermal nanoscience currently suffers from a low temperature sensitivity despite its high spatial resolution. To address this challenge, we developed a high vacuum-based AFM system hosting a highly sensitive niobium nitride (NbN) SThM probe to demonstrate its unique performance. As a proof of concept, we utilized this custom-built system to carry out thermal measurements using the 3ω method. By measuring the V3ω voltage on the NbN resistive thermometer under vacuum conditions, we were able to determine the SThM probe's thermal conductance and thermal time constant. The performance of the probe is demonstrated by performing thermal measurements in-contact with a sapphire sample. [ABSTRACT FROM AUTHOR]