(6.5)--Role of mechanical strain on the机械工程材料机械工程材料.pdf

Availableonlineat

ActaMaterialia58(2010)6619–6627

/locate/actamat

Roleofmechanicalstrainonthermalconductivityofnanoscale

aluminumfilms

H.-F.Lee,S.Kumar,M.A.Haque⇑

DepartmentofMechanicalandNuclearEngineering,ThePennsylvaniaStateUniversity,UniversityPark,PA16802,USA

Received21April2010;receivedinrevisedform15August2010;accepted18August2010

Availableonline28September2010

Abstract

Thinfilmcomponentsofconventionalandflexiblesolid-statedevicesexperiencemechanicalstrainduringfabricationandoperation.

Atthebulkscale,smallvaluesofstraindonotaffectthermalconductivity,butthismaynottrueforgrainsizescomparablewiththe

electronandphononmeanfreepathsandforhighervolumefractionofgrainboundaries.Toinvestigatethishypothesis,thermal

andelectricalconductivityofnominally125-nm-thickaluminumfilms(averagegrainsize50nm)weremeasuredasfunctionsoftensile

thermo-mechanicalstrain,usingamodifiedversionofthe3-xtechnique.Experimentalresultsshowpronouncedstrain–thermalconduc-

tivitycoupling,with50%reductioninthermalconductivityat0.25%strain.Theanalysisshowsthatmechanicalstraindecreasesthe

meanfreepathofthethermalconductionelectrons,primarilythroughenhancedscatteringatthemovinggrainboundaries.Thiscon-

clusionissupportedbysimilareffectsofmechanicalloadingobservedontheelectricalconductioninthenanoscalealuminumspecimens.

2010ActaMaterialiaInc.PublishedbyEls