We present a theory of the phononic thermal (Kapitza) resistance at the interface between graphene or another single-layer two-dimensional (2D) crystal (e.g. MoS$_{2}$) and a flat substrate, based on a modified version of the cross-plane heat transfer model by Persson, Volokitin and Ueba [J. Phys.: Condens. Matter 23, 045009 (2011)]. We show how intrinsic flexural phonon damping is necessary for obtaining a finite Kapitza resistance and also generalize the theory to encased single-layer 2D crystals with a superstrate. We illustrate our model by computing the thermal boundary conductance (TBC) for bare and SiO$_{2}$-encased single-layer graphene and MoS$_{2}$ on a SiO$_{2}$ substrate, using input parameters from first-principles calculation. The estimated room temperature TBC for bare (encased) graphene and MoS$_{2}$ on SiO$_{2}$ are 34.6 (105) and 3.10 (5.07) MWK$^{-1}$m$^{-2}$, respectively. The theory predicts the existence of a phonon frequency crossover point, below which the low-frequency flexural phonons in the bare 2D crystal do not dissipate energy efficiently to the substrate. We explain within the framework of our theory how the encasement of graphene with a top SiO$_{2}$ layer introduces new low-frequency transmission channels which significantly reduce the graphene-substrate Kapitza resistance. We emphasize that the distinction between bare and encased 2D crystals must be made in the analysis of cross-plane heat dissipation to the substrate.
We report spatially resolved measurements of static and fluctuating electric fields over conductive (Au) and non-conductive (SiO2) surfaces. Using an ultrasensitive `nanoladder' cantilever probe to scan over these surfaces at distances of a few tens of nanometers, we record changes in the probe resonance frequency and damping that we associate with static and fluctuating fields, respectively. We find that the two quantities are spatially correlated and of similar magnitude for the two materials. We quantitatively describe the observed effects on the basis of trapped surface charges and dielect…
State-of-the-art nanomechanical resonators are heralded as a central component for next-generation clocks, filters, resonant sensors and quantum technologies. To practically build these technologies will require monolithic integration of microchips, resonators and readout systems. While it is widely seen that mounting microchip substrates into a system can greatly impact the performance of high-Q resonators, a systematic study has remained elusive, owing to the variety of physical processes and factors that influence the dissipation. Here, we analytically analyze a mechanism by which substrate…
Understanding the physics underlying energy dissipation is necessary for the effective thermal management of devices based on two-dimensional (2D) materials and requires insights into the interplay between heat generation and diffusion in such materials. We review the microscopic mechanisms that govern Joule heating and energy dissipation processes in 2D materials such as graphene, black phosphorus and semiconducting transition metal dichalcogenides. We discuss the processes through which non-equilibrium charge carriers, created either transiently through photoexcitation or at steady state by …
Understanding the limits of phononic heat dissipation from a two-dimensional layered material (2DLM) to its hexagonal boron nitride (h-BN) substrate and how it varies with the structure of the 2DLM is important for the design and thermal management of h-BN-supported nanoelectronic devices. We formulate an elasticity-based theory to model the phonon-mediated heat dissipation between a 2DLM and its h-BN substrate. By treating the h-BN substrate as a semi-infinite stack of harmonically coupled thin plates, we obtain semi-analytical expressions for the thermal boundary conductance (TBC) and interf…
Compared to nanoscale friction of translational motion, the mechanisms of rotational friction have received less attention. Such motion becomes an important issue for the miniaturization of mechanical machineries which often involve rotating gears. In this study, molecular dynamics simulations are performed to explore rotational friction for solid-state gears rotating on top of different substrates. In each case, viscous damping of the rotational motion is observed and found to be induced by the pure van-der-Waals interaction between gear and substrate. The influence of different gear sizes an…
Efficient heat dissipation to the substrate is crucial for optimal device performance in nanoelectronics. We develop a theory of electronic thermal boundary conductance (TBC) mediated by remote phonon scattering for the single-layer transition metal dichalcogenide (TMD) semiconductors MoS$_{2}$ and WS$_{2}$, and model their electronic TBC with different dielectric substrates (SiO$_{2}$, HfO$_{2}$ and Al$_{2}$O$_{3}$). Our results indicate that the electronic TBC is strongly dependent on the electron density, suggesting that it can be modulated by the gate electrode in field-effect transistors,…
Dissipation effects in the Su-Schrieffer-Heeger model coupled to a metallic environment
Instituto Interdisciplinario de Ciencias Básicas (ICB-CONICET), Universidad Nacional de Cuyo（门多萨国立大学基础科学跨研究所）；Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo（门多萨国立大学理学院）
Membrane amplitude and triaxial stress in twisted bilayer graphene deciphered using first-principles directed elasticity theory and scanning tunneling microscopy
Graphene-enabled, directed nanomaterial placement from solution for large-scale device integration
纳米材料在预定位置以纳米级精度的受控放置仍然是最具挑战性的问题之一，其抑制了它们在半导体工艺技术领域中的大规模集成。基于表面功能化的方法具有缺点，其中可能发生不期望的化学改性并使沉积的材料劣化。电场辅助放置技术的应用消除了化学处理的元素;然而，它需要结合限制集成电子器件的性能、缩放和密度的导电放置电极。在这里，我们报告了一种方法，电场辅助放置的解决方案处理的纳米材料，通过使用大规模的石墨烯层具有纳米级的沉积网站。结构化的石墨烯层通过转移或合成在标准基底上制备，然后一旦纳米材料沉积完成就被无残留地去除，产生具有纳米级分辨率的材料组件，其覆盖的表面积大于1 mm 2。为了证明其广泛的适用性，我们在预定义的衬底位置组装了具有代表性的零维、一维和二维半导体，并将其集成到纳米电子器件中。这种基于石墨烯的放置技术提供了晶圆级的纳米级分辨率，并且可以实现涉及通过基于溶液的方法制备的各种纳米材料的纳米电子器件和光电子器件的大规模制造。
An Ultra-Sub-Wavelength Microwave Polarization Switching Antenna for Covert Communication Implemented With Directed Surface Acoustic Waves in an Artificial Multiferroic Magnonic Crystal
