ACS Appl Mater Interfaces
October 2024
Thermal resistance at interfaces/contacts stands as a persistent and increasingly critical issue, which hinders ultimate scaling and the performance of electronic devices. Compared to the extensive research on contact electrical resistance, contact thermal resistance and its mitigation strategies have received relatively less attention. Here, we report on an effective, in situ, and energy-efficient approach for enhancing thermal transport through the contact between semiconducting nanoribbons.
View Article and Find Full Text PDFEfficient heat dissipation is crucial for the performance and lifetime of high electron mobility transistors (HEMTs). The thermal conductivity of materials and interfacial thermal conductance (ITC) play significant roles in their heat dissipation. To predict the thermal properties of AlxGa1-xN and the ITC of GaN/AlxGa1-xN in HEMTs, a dataset with first-principles accuracy was constructed using concurrent learning method and trained to obtain an interatomic potential employing deep neural networks (DNN) method.
View Article and Find Full Text PDF4H-silicon carbide (4H-SiC) possesses a high Baliga figure of merit, making it a promising material for power electronics. However, its applications are limited by low hole mobility. Herein, we found that the hole mobility of 4H-SiC is mainly limited by the strong interband electron-phonon scattering using mode-level first-principles calculations.
View Article and Find Full Text PDFThis study addresses a crucial challenge in two-dimensional (2D) material-based electronic devices-inefficient heat dissipation across the van der Waals (vdW) interface connecting the 2D material to its three-dimensional (3D) substrate. The objective is to enhance the interfacial thermal conductance (ITC) of 2D/3D heterostructures without compromising the intrinsic thermal conductivities (κ) of 2D materials. Using 2D-MoS/3D-GaN as an example, a novel strategy to enhance both the ITC across 2D/3D interface and κ of 2D material is proposed by introducing a controlled concentration (ρ) of vacancy defects to substrate's bottom surface.
View Article and Find Full Text PDFPhys Chem Chem Phys
March 2024
An amorphous layer is commonly found at the interfaces of heterostructures due to lattice and thermal mismatch between dissimilar materials. While existing research has explored the impact of these layers on interfacial thermal transport, a comprehensive understanding of the underlying microscopic mechanisms remains essential for advancing thermal nanodevice development. Through phonon wave packet simulations, we investigated the dynamic behaviors of phonons crossing the amorphous interlayer at the GaN/AlN interface from the mode level.
View Article and Find Full Text PDFFlexible, lightweight, and low-cost thermoelectric thin films are promising for self-powered wearable electronics and sensors. In this work, we report on flexible Te nanostructures/PEDOT:PSS composite thin films with high power factor and their application as flexible temperature sensors. Te nanostructures with high crystallinity and high aspect ratios were synthesized through an environmentally friendly method without using highly toxic chemicals.
View Article and Find Full Text PDFHeat dissipation in two-dimensional (2D) material-based electronic devices is a critical issue for their applications. The bottleneck for this thermal issue is inefficient for heat removal across the van der Waals (vdW) interface between the 2D material and its supporting three-dimensional (3D) substrate. In this work, we demonstrate that an atomic-scale thin amorphous layer atop the substrate surface can remarkably enhance the interfacial thermal conductance (ITC) of the 2D-MoS/3D-GaN vdW interface by a factor of 4 compared to that of the untreated crystalline substrate surface.
View Article and Find Full Text PDFRealizing switchable n-type and p-type conduction in bismuth selenide (BiSe), a traditional thermoelectric material and a topological insulator, is highly beneficial for the development of thermoelectric devices and also of great interest for spintronics and quantum computing. In this work, switching between n-type and p-type conduction in single BiSe nanoribbons is achieved by a reversible copper (Cu) intercalation method. Density functional theory calculations reveal that such a switchable behavior arises from the electronic band structure distortion caused by the high-concentration Cu intercalation and the Cu substitution for Bi sites in the host lattice.
View Article and Find Full Text PDFElectrical and thermal transport through metal point contacts, a key issue in the design and operation of various engineering devices, is of great recent interest. The effective Lorenz number (), which relates the thermal to electrical conductance of point contacts, could provide valuable information on the relative contribution of electrons and phonons to thermal transport. Through measuring electrical and thermal transport across point contacts between silver nanowires, we report that significantly deviates from the Sommerfeld value by up to 5.
View Article and Find Full Text PDFIn this work, we experimentally investigated the effect of sulfur passivation on thermal transport in indium arsenide (InAs) nanowires. Our measurement results show that thermal conductivity can be enhanced by a ratio up to 159% by sulfur passivation. Current-voltage (I-V) measurements were performed on both unpassivated and S-passivated InAs nanowires to understand the mechanism of thermal conductivity enhancement.
View Article and Find Full Text PDFThis paper presents a setup for measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials. The sample holder was designed to have a compact structure and can be directly mounted in a standard cryostat system for temperature-dependent measurements. For the Seebeck coefficient measurement, a thin bar-shaped sample is mounted bridging two copper bases; and two ceramic heaters are used to generate a temperature gradient along the sample.
View Article and Find Full Text PDFThe ability to control thermal conductivity is important in a wide variety of applications, especially in heat removal, heat insulation, and thermoelectric energy conversion. Herein, we reveal that the thermal conductivity of epoxy resin fibers increases on decreasing the fiber diameter and surpasses the bulk value (0.25 W m K at 300 K) for the fiber with a diameter of 211 nm.
View Article and Find Full Text PDFThis work reports a thermal transport study in quasi-one-dimensional organic nanostructures self-assembled from conjugated planar molecules via π-π interactions. Thermal resistances of single crystalline copper phthalocyanine (CuPc) and perylenetetracarboxylic diimide (PTCDI) nanoribbons are measured via a suspended thermal bridge method. We experimentally observed the deviation from the linear length dependence for the thermal resistance of single crystalline β-phase CuPc nanoribbons, indicating possible subdiffusion thermal transport.
View Article and Find Full Text PDFBismuth selenide (Bi2Se3) nanoribbons have attracted tremendous research interest recently to study the properties of topologically protected surface states that enable new opportunities to enhance the thermoelectric performance. However, the thermoelectric characterization of individual Bi2Se3 nanoribbons is rare due to the technological challenges in the measurements. One challenge is to ensure good contacts between the nanoribbon and electrodes in order to determine the thermal and electrical properties accurately.
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