High Temperature Near-Field NanoThermoMechanical Rectification

Abstract

Limited performance and reliability of electronic devices at extreme temperatures, intensive electromagnetic fields, and radiation found in space exploration missions (i.e., Venus & Jupiter planetary exploration, and heliophysics missions) and earth-based applications requires the development of alternative computing technologies. In the pursuit of alternative technologies, research efforts have looked into developing thermal memory and logic devices that use heat instead of electricity to perform computations. However, most of the proposed technologies operate at room or cryogenic temperatures, due to their dependence on material’s temperature-dependent properties. Here in this research, we show experimentally—for the first time—the use of near-field thermal radiation (NFTR) to achieve thermal rectification at high temperatures, which can be used to build high-temperature thermal diodes for performing logic operations in harsh environments. We achieved rectification through the coupling between NFTR and the size of a micro/nano gap separating two terminals, engineered to be a function of heat flow direction. We fabricated and tested a proof-of-concept NanoThermoMechanical device that has shown a maximum rectification of 10.9% at terminals’ temperatures of 375 and 530 K. Experimentally, we operated the microdevice in temperatures as high as about 600 K, demonstrating this technology’s suitability to operate at high temperatures.

Thermal diodes, regulators, and switches: Physical mechanisms and potential applications

“…Recent room temperature measurements 280 showed r as large as 100-1000 for SiO 2 -SiO 2 surfaces or Au-Au surfaces as the gap was reduced to L < 100 nm. For larger values of L ¼ 3 lm, Elzouka and Ndoa 281 reported thermal rectifications of 10% at DT ¼ 150 K using the asymmetric thermal expansion of a MEMS structure to control L. Overall, for the purpose of thermal switching it is likely more practical (and effective 282 ) to bring materials fully in and out of contact (see Sec. III A 4) than to rely on near field mechanisms, since it is difficult to maintain and control such small yet finite L over macroscopic distances.…”

A near-field radiative heat transfer device

“…1a. It consists of a high-temperature emitter and low-temperature receiver made of Si, with boron doping of ~ 4.6×10 19 cm -3 , separated by low thermal conductivity SU-8 3005 micropillars (0.2 Wm -1 K -1 ) 22 the emitter and receiver, thus minimizing the contribution of parasitic conduction to the total heat rate 23 . The micropillar and pit areas respectively cover 0.01% and less than 1.2% of the total surface of the device.…”

NanoThermoMechanical AND and OR Logic Gates

“…Microfabrication process. The proposed microdevices were fabricated using cleanroom standard microfabrication techniques starting with a four-inch-diameter <100> silicon on insulator (SOI) wafer 16 . The SOI wafer consisted of a 400-μm thick handle silicon substrate, a 1-μm thick buried silicon dioxide layer, and a 20-μm thick boron-doped silicon device layer.…”

“…The characterization and heat transfer measurements of the thermal logic gates were performed inside a vacuum probe station at vacuum levels below 10 −5 mbar, in order to eliminate convection and conduction heat losses 16 . The platinum microheaters patterned on the mechanisms were powered independently via two source-meter units (Keithley 2602 B andKeithley 2611 B).…”