Recent years have seen a rapid growth of interest by the scientific and engineering communities in the thermal properties of materials. Heat removal has become a crucial issue for continuing progress in the electronic industry, and thermal conduction in low-dimensional structures has revealed truly intriguing features. Carbon allotropes and their derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range--of over five orders of magnitude--from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. Here, I review the thermal properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. Special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe the prospects of applications of graphene and carbon materials for thermal management of electronics.

Thermal properties of graphene and nanostructured carbon materials

Recent years witnessed a rapid growth of interest of scientific and engineering communities to thermal properties of materials. Carbon allotropes and derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range – of over five orders of magnitude – from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. I review thermal and thermoelectric properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. A special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe prospects of applications of graphene and carbon materials for thermal management of electronics.

Thermal Properties of Graphene, Carbon Nanotubes and Nanostructured Carbon Materials

The isolation of graphene in 2004 from graphite was a defining moment for the “birth” of a field: two-dimensional (2D) materials In recent years, there has been a rapidly increasing number of papers focusing on non-graphene layered materials, including transition-metal dichalcogenides (TMDs), because of the new properties and applications that emerge upon 2D confinement Here, we review significant recent advances and important new developments in 2D materials “beyond graphene” We provide insight into the theoretical modeling and understanding of the van der Waals (vdW) forces that hold together the 2D layers in bulk solids, as well as their excitonic properties and growth morphologies Additionally, we highlight recent breakthroughs in TMD synthesis and characterization and discuss the newest families of 2D materials, including monoelement 2D materials (ie, silicene, phosphorene, etc) and transition metal carbide- and carbon nitride-based MXenes We then discuss the doping and functionalization of 2

Recent Advances in Two-Dimensional Materials beyond Graphene

Emerging challenges and materials for thermal management of electronics

Fast, cheap, and reliable DNA sequencing could be one of the most disruptive innovations of this decade, as it will pave the way for personalized medicine. In pursuit of such technology, a variety of nanotechnology-based approaches have been explored and established, including sequencing with nanopores. Owing to its unique structure and properties, graphene provides interesting opportunities for the development of a new sequencing technology. In recent years, a wide range of creative ideas for graphene sequencers have been theoretically proposed and the first experimental demonstrations have begun to appear. Here, we review the different approaches to using graphene nanodevices for DNA sequencing, which involve DNA passing through graphene nanopores, nanogaps, and nanoribbons, and the physisorption of DNA on graphene nanostructures. We discuss the advantages and problems of each of these key techniques, and provide a perspective on the use of graphene in future DNA sequencing technology.

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Graphene nanodevices for DNA sequencing

Self-heating is a severe problem for high-power gallium nitride (GaN) electronic and optoelectronic devices. Various thermal management solutions, for example, flip-chip bonding or composite substrates, have been attempted. However, temperature rise due to dissipated heat still limits applications of the nitride-based technology. Here we show that thermal management of GaN transistors can be substantially improved via introduction of alternative heat-escaping channels implemented with few-layer graphene-an excellent heat conductor. The graphene-graphite quilts were formed on top of AlGaN/GaN transistors on SiC substrates. Using micro-Raman spectroscopy for in situ monitoring we demonstrated that temperature of the hotspots can be lowered by ∼20 °C in transistors operating at ∼13 W mm(-1), which corresponds to an order-of-magnitude increase in the device lifetime. The simulations indicate that graphene quilts perform even better in GaN devices on sapphire substrates. The proposed local heat spreading with materials that preserve their thermal properties at nanometre scale represents a transformative change in thermal management.

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Graphene quilts for thermal management of high-power GaN transistors

We review thermal properties of graphene and few-layer graphene, and discuss applications of these materials in thermal management of advanced electronics The intrinsic thermal conductivity of graphene - among the highest of known materials - is dominated by phonons near the room temperature The examples of thermal management applications include the few-layer graphene heat spreaders integrated near the heat generating areas of the high-power density transistors It has been demonstrated that few-layer graphene heat spreaders can lower the hot-spot temperature during device operation resulting in improved performance and reliability of the devices

Review of Thermal Properties of Graphene and Few-Layer Graphene: Applications in Electronics

The authors review thermal properties of graphene and few-layer graphene (FLG), and discuss applications of these materials in thermal management of advanced electronics. The intrinsic thermal conductivity of graphene - among the highest of known materials - is dominated by phonons near the room temperature. The examples of thermal management applications include the FLG heat spreaders integrated near the heat generating areas of the high-power density transistors. It has been demonstrated that FLG heat spreaders can lower the hot-spot temperature during device operation, resulting in improved performance and reliability of the devices.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-cds.2014.0093

Thermal properties of graphene and few-layer graphene: applications in electronics

The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the process can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. In addition, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics. Direct growth of large-area graphene on dielectric substrates is a promising route to wafer scale integration. Here the authors use a rapid thermal annealing process to grow graphene layers on four-inch diameter polycrystalline diamond, eliminating the need for transfer.

/pdf/metal-induced-rapid-transformation-of-diamond-into-single-1re55radd8.pdf

Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

Patterning of biomolecules on graphene layers could provide new avenues to modulate their electrical properties for novel electronic devices. Single-stranded deoxyribonucleic acids (ssDNAs) are found to act as negative-potential gating agents that increase the hole density in single-layer graphene. Current-voltage measurements of the hybrid ssDNA/graphene system indicate a shift in the Dirac point and "intrinsic" conductance after ssDNA is patterned. The effect of ssDNA is to increase the hole density in the graphene layer, which is calculated to be on the order of 1.8 x 10(12) cm(-2). This increased density is consistent with the Raman frequency shifts in the G-peak and 2D band positions and the corresponding changes in the G-peak full width at half maximum. Ab initio calculations using density functional theory rule out significant charge transfer or modification of the graphene band structure in the presence of ssDNA fragments.

Zhong Yan

Papers

Graphene quilts for thermal management of high-power GaN transistors

Review of Thermal Properties of Graphene and Few-Layer Graphene: Applications in Electronics

Thermal properties of graphene and few-layer graphene: applications in electronics

Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

Gating of Single‐Layer Graphene with Single‐Stranded Deoxyribonucleic Acids