Feasibility, accuracy, and performance of contact block reduction method for multi-band simulations of ballistic quantum transport

Abstract

Numericalutilitiesofthecontactblockreduction(CBR)methodinevaluatingtheretardedGreen’sfunctionarediscussedfor3Dmulti-bandopensystemsthatarerepresentedbytheatomictight-binding(TB)andcontinuumk.p(KP)bandmodel.Itisshownthatthemethodologytoapproximatesolutionsofopensystems,whichhasbeenalreadyreportedforthesingle-bandeffectivemassmodel,cannotbedirectlyusedforatomicTBsystems,sincetheuseofasetofzincblendecrystalgridsmakestheinter-couplingmatrixnon-invertible.WederiveandtestanalternativewithwhichtheCBRmethodcanbestillpracticalinsolvingTBsystems.Thismulti-bandCBRmethodisvalidatedbyaproofofprinciplesonsmallsystemsandalsoshowntoworkexcellentwiththeKPapproach.Furtherdetailedanalysisontheaccuracy,speed,andscalabilityonhighperformancecomputingclustersisperformedwithrespecttothereferenceresultsobtainedbythestate-of-the-artrecursiveGreen’sfunctionandwavefunctionalgorithm.ThisworkshowsthattheCBRmethodcouldbeparticularlyusefulincalculatingresonanttunnelingfeatures,butshowsalimitedpracticalityinsimulatingfieldeffecttransistors(FETs)whenthesystemisdescribedwiththeatomicTBmodel.CoupledtotheKPmodel,however,theutilityoftheCBRmethodcanbeextendedtosimulationsofnanowireFETs.