Multi-scale study of electronic and thermal transport properties for the Cu/diamond interface

Abstract

<p indent="0mm">As a wide bandgap semiconductor, diamond has not only excellent electrical qualities but also extremely high thermal conductivity, allowing it to withstand high breakdown voltage while swiftly dissipating heat. As a result, diamond-based high-power devices are becoming increasingly popular. Cu, a transition metal with a high work function, is widely used in semiconductor microfabrication and possesses outstanding heat dissipation properties comparable to diamond. Therefore, that Cu-covered diamond is beyond the significance of ordinary electrodes. This type of metal-semiconductor contact may modify interfacial electrical features while simultaneously performing thermal design and management functions. The electrical characteristics of the Cu/diamond contact are studied using a first-principles method based on hybrid density functional theory. The Schottky barrier height of the Cu/diamond interface is 1.60 eV, according to the findings. The electron rearrangement within one or two atomic layers near the interface is revealed by the atomic layer resolved density of states and Bader charge transfer analysis, which indicates that charge reconstruction induced by the interface mainly results from metal-induced band gap states. The thermal characteristics of Cu, diamond, and Cu/diamond interface materials are also investigated using density functional perturbation theory, anharmonic approximation, and the phonon Boltzmann transport equation. The thermal conductivities of diamond and Cu are 2501.3 and <sc>410.4 W m</sc>⁻¹ K⁻¹ at room temperature, respectively. And for the Cu/diamond interface, the interfacial thermal conductance of <sc>27.87 MW m</sc>⁻² K⁻¹ at room temperature is obtained through the Diffuse Mismatch Models. The computed value may be less than the experimental data because electron-phonon coupling contributions were not considered. Furthermore, the Hasselman-Johnson model is used to determine the relationship between the effective thermal conductivity of the Cu/diamond system and the size of the material system and the volume fraction of the diamond at room temperature. These theoretical results are consistent with the experimental results. As a result, all these results suggest that transition metal Cu as a surface coating has important applications in diamond-based high-power electronic devices.</p>

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