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　　采用電子密度泛函理論方法計算了一系列（111）方向的InAs/GaSb超晶格的電子結構和能帶結構.將雜化泛函的計算結果與普通密度泛函方法的計算結果進行了比較.Heyd-Scuseria-Ernzerhof（HSE）雜化與對固體修正的Perdew-Burke-Ernzerhof（PBE）近似結合的雜化泛函顯示了較傳統(tǒng)PBE方法和若干其他雜化泛函更符合實驗數據的結果.采用該方法研究了InAs/GaSb超晶格的帶隙隨超晶格周期厚度以及InAs/GaSb比例變化的規(guī)律.其結果與以往實驗結果符合很好.這些結果表明HSE-PBEsol方法對于估計InAs/GaSb超晶格的電子性質適用. 

【文章來源】：紅外與毫米波學報. 2016,35(06)北大核心EISCICSCD

【文章頁數】：6 頁

【部分圖文】：

PBE和HSE-PBEsol方法計算所得InAs和GaSb晶體的能帶結構(計算中InAs和GaSb的費米能級分別為2．93eV、3．68eV，該值僅具有相對比較意義)

(InAs)7/(GaSb)7superlattice(4．2μm)［5］andof(InAs)10/(GaSb)10su-perlattice(5．6μm)［12］．Theseresultsindicatethero-bustperformanceofHSE-PBEsolmethodinInAs/GaSbsuperlatticesystems．Asaroughestimation，wecanex-trapolatethebandgapwouldvanishwhentheperiodicthicknessincreasestoover160?．Fig．3Bandgapchangeswiththeperiodicthicknessofthe(I-nAs)n/(GaSb)nsuperlatticestructures．(n=1，2，3，6，9)圖3帶隙隨(InAs)n/(GaSb)n超晶格結構周期厚度變化圖(n=1，2，3，6，9)Thesharpdecreaseofthebandgapwithperiodicthicknessdecreasewhenn＜3iscounter-intuitive．How-ever，inviewofthat(InAs)1/(GaSb)1isverysimilarto(GaAs)1/(InSb)1(thetwosymbolsareidenticalin(100)directionandslightlydifferentinbondingin(111)direction)，theperfect(GaAs)1/(InSb)1struc-tureshoulddisplayabandgapsmallerthanInSb(0．24eV)．Thiseffectwillrapidlybeneutralizedbythein-creaseofperiodicthickness．Thisargumentcanbesup-portedbydistributionchangeofthevalencebandmaxi-mum(VBM)andconductionbandminimum(CBM)withtheperiodicthickness．AsshowninFig．4，whenn＞3，the(InAs)n/(GaSb)nsupperlatticesaretypicaltype-IIsuperlatticeswithsignificantelectron-holesepara-tion．However，whenn＜3，theincreaseofelectronden-sityattheIn-SbinterfaceandtheincreaseofholedensityattheGa-Asinterfacecanbeobserved．Itmeansthatthesesuperlatticeswithultra-short

ngoodconsistencywiththeexperimentalmeasurementofthecut-offwave-lengthof(InAs)9/(GaSb)12(4．6μm)［19］．TakingtheblueshiftcausedbytheincreasedthicknessofGaSbintoconsideration，wesupposetheHSE-PBEsolmethodcom-binedwithstandardInAs/GaSbmodelsshowsverypres-entreliablepredicitionofbandgappropertiesofInAs/GaSbsuperlatticesystems．Fig．7Bandgapandcut-offwavelengthchangesof(InAs)m/(GaSb)nsuperlatticestructureswithdifferentthicknessesofInAs圖7帶隙和截止波長隨(InAs)m/(GaSb)n超晶格結構中I-nAs層厚度變化圖Indirect-gapsemiconductors，absorptioncoefficientisinverselyproportionaltothefilmthickness．Soachie-vingthetargetcut-offwavelengthinminimumperiodicthicknessisanimportantdesignprincipleofInAs/GaSbsuperlatticedetectors．Thecut-offwavelengthcanbead-justedbychangingtheInAs/GaSbratioinInAs/GaSbsuperlatticeofacertainperiodicthickness．Thevaria-tionsofbandgapandcut-offwavelengthofInAs/GaSbsuperlatticewithequalperiodicthicknesswhiledifferentthicknessesofInAsareshowninFig．8．AseriesofI-nAs/GaSbsuperlatticeof12/15MLthickwithInAsthicknesschangingfrom3MLto12MLwerepresent．Theresultsindicatethattherangeofcut-offwavelengthfrom4μmto10μmcanbeachievedinInAs/GaSbsuper-latticeof15MLthick．3ConclusionElectronicstructuresandbandstructuresofaseriesofInAs/GaSbsuperlatticewerecalculatedbyDFTmeth-od．HybridfunctionalmethodswereappliedinDFTcal-culationsandcomparedwithconv

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期刊論文
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