Low-Cost Nanostructures from Nanoparticle-Assisted Large-Scale Lithography Significantly Enhance Thermal Energy Transport across Solid Interfaces

Abstract

Enhancing thermal energy transport across solid interfaces is of critical importance to a wide variety of applications ranging from energy systems and lighting devices to electronics. Nanoscale surface roughness is usually considered detrimental to interfacial thermal transport because of its role in phonon scattering. In this study, however, we demonstrate significant thermal conductance enhancements across metal-semiconductor interfaces by as much as 90% higher than that of the planar interfaces using engineered nanostructures fabricated by Au nanoparticle (NP)-assisted lithography, where self-assembled Au NPs are used as an efficient etching mask to pattern solid substrates over large surface areas. The enlarged interfacial contact area due to the presence of nanostructures is the main reason for the significantly enhanced thermal transport. It is further demonstrated that the conductance can be systematically tuned over a wide range through the use of the Au NP self-assembly process that is regulated by a sacrificial Sb layer whose thickness determines the size and density of the nanostructures produced. This strategy is tested on two technologically important semiconductors, Si and GaN, and their interfacial thermal conductance with Al being measured using the time-domain thermoreflectance technique. Moreover, the nanostructured interfaces can maintain the enhanced conductance for a temperature range of 30-110 °C-the operating temperatures commonly experienced by energy, lighting, and electronic devices. Our results could provide a wafer-scale and low-cost strategy for improving the thermal management of these devices.

High thermal conductive copper/diamond composites: state of the art

“…22, can also enhance the TBC between Si and Al [95]. Compared to the planar surface, the rough surface caused by the formed nanopillar has a larger effective contact area, contributing to the significant increase in TBC up to 90% [95].…”

“…SEM images of a periodic and b random nanopillars fabricated on Si substrates using EBL, c schematic of a nanostructured Si surface capped with a 100-nm Al layer as the TBC is being monitored by TDTR, d schematic illustration of thermal transport enhancement by a nanopillar in comparison with the case of a planar interface (dotted lines indicate that heat can also pass through the sidewall of the nanopillar to cross the interface) and e normalized TBC as a function of the number density of nanopillars for the periodic (circle) and random (square) nanostructured Si/Al interfaces[95].…”

Effects of interfaces and current spreading on the thermal transport of micro-LEDs for kA-per-square-cm current injection levels

“…7 Some interface structures, such as GaN-diamond interface, GaN/SiC nano-pillar and nano-patterned substrates are applied to enhance the transport of phonons at the interface. 20,26,27 Thermal engineering of the materials and their interfaces should also be an important issue for mLEDs under high injection levels.…”

“…Many techniques have been developed to characterize the thermal properties of multilayer materials. 6,7,10,[19][20][21]24,[27][28][29][30][31][32] Micro-Raman spectroscopy provides a temporal, spectral and spatial resolution for thermal measurement. 27 The micron-class spatial resolution cannot satisfy the specic structure of an LED.…”

“…6,7,10,[19][20][21]24,[27][28][29][30][31][32] Micro-Raman spectroscopy provides a temporal, spectral and spatial resolution for thermal measurement. 27 The micron-class spatial resolution cannot satisfy the specic structure of an LED. The absorption for the excitation and Raman scattering of light in different layers should cause large measurement errors.…”