Micron-gap spacers with ultrahigh thermal resistance and mechanical robustness for direct energy conversion Samuel

作     者：M.Nicaise Chen Lin Mohsen Azadi Tara Bozorg-Grayeli Promise Adebayo-Ige Drew E.Lilley Yann Pfitzer Wujoon Cha Kyana Van Houten Nicholas A.Melosh Roger T.Howe Jared W.Schwede Igor Bargatin 

作者机构：Mechanical Engineering and Applied MechanicsUniversity of PennsylvaniaPhiladelphiaPA 19104USA Materials Science&EngineeringStanford UniversityStanford 94305 CAUSA Chemical and Biomolecular EngineeringUniversity of PennsylvaniaPhiladelphiaPAUSA Spark ThermionicsBerkeleyCA 94720USA Electrical EngineeringStanford UniversityStanfordCA 94305USA 

出 版 物：《Microsystems & Nanoengineering》 (微系统与纳米工程（英文）)

年 卷 期：2019年第5卷第1期

页      面：344-355页

核心收录：

学科分类：08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 

基　　金：The information,data,or work presented herein was funded in part by the Advanced Research Projects Agency-Energy(ARPA-E),U.S.Department of Energy,under Award No.DE-AR0000664 This work was carried out in part at the Singh Center for Nanotechnology at the University of Pennsylvania,a member of the National Nanotechnology Coordinated Infrastructure(NNCI)network,which is supported by the National Science Foundation(Grant No.ECCS-1542153) 

主　　题：thermal resistance film 

摘      要：In thermionic energy converters,the absolute efficiency can be increased up to 40%if space-charge losses are eliminated by using a sub-10-μm gap between the *** practical way to achieve such small gaps over large device areas is to use a stiff and thermally insulating spacer between the two *** report on the design,fabrication and characterization of thin-film alumina-based spacers that provided robust 3–8μm gaps between planar substrates and had effective thermal conductivities less than those of *** spacers were fabricated on silicon molds and,after release,could be manually transferred onto any *** large-scale compression testing,they sustained compressive stresses of 0.4–4 MPa without ***,the thermal conductance was 10–30 mWcm^(−2)K^(−1)and,surprisingly,independent of film thickness(100–800 nm)and spacer *** explain this independence,we developed a model that includes the pressure-dependent conductance of locally distributed asperities and sparse contact points throughout the spacer structure,indicating that only 0.1–0.5%of the spacerelectrode interface was conducting *** spacers show remarkable functionality over multiple length scales,providing insulating micrometer gaps over centimeter areas using nanoscale *** innovations can be applied to other technologies requiring high thermal resistance in small spaces,such as thermophotovoltaic converters,insulation for spacecraft and cryogenic devices.