Kangangeminyaka emininzi, izazinzulu ezivela kwihlabathi liphela bezisenza izinto ezimbini – ukuqamba nokuphucula. Kwaye ngamanye amaxesha akucaci ukuba yintoni enzima ngakumbi. Thatha, umzekelo, ii-LED eziqhelekileyo, ezibonakala zilula kwaye ziqhelekile kuthi kangangokuba asizihoyi. Kodwa ukuba wongeza ii-excitons ezimbalwa, i-pinch ye-polaritons kunye ne-tungsten disulfide ukunambitha, ii-LED azisayi kuba yiprosaic. Onke la magama angabonakaliyo ngamagama eenxalenye ezingaqhelekanga kakhulu, indibaniselwano eyavumela izazinzulu ezivela kwiKholeji yesiXeko saseNew York ukuba zenze inkqubo entsha ekwaziyo ukusasaza ulwazi ngokukhawuleza kusetyenziswa ukukhanya. Olu phuhliso luya kunceda ukuphucula ubuchwepheshe be-Li-Fi. Ziziphi izithako ezichanekileyo zeteknoloji entsha ezisetyenzisiweyo, yintoni iresiphi yesi "sitya" kwaye yintoni ukusebenza kakuhle kwe-LED entsha ye-exciton-polariton? Ingxelo yezazinzulu iya kusixelela ngale nto. Hamba.
Isiseko sophando
Ukuba silula yonke into phantsi kwegama elinye, ke le teknoloji ilula kwaye yonke into idibene nayo. Okokuqala, i-polaritons, ephuma xa iifotoni zidibanisa kunye no-excitations we-medium (phonon, excitons, plasmons, magnons, njl.). Okwesibini, i-excitons yi-excitations ye-elektroniki kwi-dielectric, i-semiconductor okanye isinyithi esifuduka kuyo yonke i-crystal kwaye ayihambelani nokudluliselwa kwentlawulo yombane kunye nobunzima.
Kubalulekile ukuba uqaphele ukuba ezi quasiparticles zithanda ukubanda kakhulu, okt. Umsebenzi wabo unokujongwa kuphela kumaqondo obushushu aphantsi kakhulu, nto leyo ethintela kakhulu ukusetyenziswa kwawo okusebenzayo. Kodwa oko kwakungaphambili. Kulo msebenzi, izazinzulu ziye zakwazi ukunqoba umlinganiselo weqondo lokushisa kwaye ziwasebenzise kumaqondo obushushu begumbi.
Into ephambili ye-polaritons kukukwazi ukubopha iifotoni kunye nomnye. Iifoto ezingqubana neeathom zerubidium zifumana ubunzima. Kwinkqubo yokungqubana okuphindaphindiweyo, i-photons idibanisa enye kwenye, kodwa kwiimeko ezinqabileyo zenza izibini kunye ne-triplets, ngelixa zilahlekelwa yicandelo le-athomu elimelwe yi-athomu ye-rubidium.
Kodwa ukwenza into ngokukhanya, kufuneka uyibambe. Kule nto, i-resonator ye-optical iyadingeka, eyisethi yezinto ezikhanyayo ezenza ukukhanya okumileyo.
Kule sifundo, indima ebaluleke kakhulu idlalwa yi-quasiparticles engaqhelekanga ngakumbi - i-exciton-polaritons, eyenziwa ngenxa yokudibanisa okunamandla kwe-excitons kunye neefotoni ezibanjwe kwi-optical cavity.
Noko ke, oku akwanelanga, kuba isiseko sezinto eziphathekayo siyafuneka, ngokungathi kunjalo. Kwaye ngubani ongcono kune-transition metal dichalcogenide (TMD) eya kudlala le ndima? Ngokuchanekileyo, i-WS2 (i-tungsten disulfide) i-monolayer isetyenziswe njengezinto ezikhuphayo, ezinamandla okubopha i-exciton, eyaba yenye yeendlela eziphambili zokukhetha isiseko sezinto eziphathekayo.
Ukudityaniswa kwazo zonke izinto ezichazwe ngasentla kwenza ukuba kube lula ukwenza i-LED ye-polariton elawulwa ngombane esebenza kwiqondo lokushisa.
Ukuqonda esi sixhobo, i-monolayer ye-WS2 ifakwe phakathi kwezithintelo zetonela ze-boron nitride (hBN) ezibhityileyo ezinomaleko wegraphene osebenza njengee-electrode.
Iziphumo zophando
I-WS2, iyintsimbi yenguqu idichalcogenide, ikwayinto ebhityileyo ye-atomically van der Waals (vdW). Oku kuthetha umbane wayo okhethekileyo, optical, mechanical and thermal properties.
Ngokudibanisa nezinye izinto ze-vdW, ezifana negraphene (njengomqhubi) kunye ne-hexagonal boron nitride (hBN, njenge-insulator), yonke inkitha yezixhobo ze-semiconductor ezilawulwa ngombane, ezibandakanya ii-LED, zinokuqondwa. Iindibaniselwano ezifanayo zemathiriyeli ye-van der Waals kunye nee-polaritons sele ziqatshelwe ngaphambili, njengoko abaphandi bechaza ngokuphandle. Nangona kunjalo, kwimisebenzi yangaphambili, iinkqubo ezibangelwayo zazinzima kwaye zingafezekanga, kwaye azizange zibonakalise amandla apheleleyo ecandelo ngalinye.
Enye yeengcamango eziphefumlelweyo ngabanduleli yayikukusetyenziswa kweqonga lezinto ezimbini. Kule meko, kunokwenzeka ukuqaphela izixhobo ezineeleko ze-atomically ezincinci ezikhuphayo, ezinokudityaniswa nezinye izinto ze-vdW ezisebenza njengabafowunelwa (igraphene) kunye nezithintelo zetonela (hBN). Ukongeza, loo macala mabini enza ukuba kube lula ukudibanisa ii-LED ze-polariton kunye nezixhobo ze-vdW ezineempawu ezingaqhelekanga zamagnetic, i-superconductivity eyomeleleyo kunye / okanye i-non-standard topological transfers. Ngenxa yokudibanisa okunjalo, uhlobo olutsha ngokupheleleyo lwesixhobo lunokufumaneka, iipropati ezinokuthi zingaqhelekanga. Kodwa, njengoko izazinzulu zisitsho, esi sisihloko solunye uphononongo.
Umfanekiso #1
Kumfanekiso 1 ibonisa imodeli ye-dimensional emithathu yesixhobo efana neqebengwana lekhekhe. Isibuko esiphezulu se-resonator ye-optical ngumaleko wesilivere, kwaye isibuko esisezantsi si-12-layer isasazwa. Bragg reflector*. Indawo esebenzayo iqulathe indawo yetonela.
Usasazo lwesibonisi seBragg* - isakhiwo semigangatho emininzi apho isalathiso se-refractive sezinto eziphathekayo sitshintsha ngokuthe rhoqo kwi-perpendicular to layers.
Ummandla wetonela uquka i-heterostructure ye-vdW equka i-WS2 monolayer (i-emitter yokukhanya), iileya ezincinci ze-hBN kumacala omabini e-monolayer (umqobo wetonela) kunye ne-graphene (i-electrode ecacileyo yokwazisa i-electron kunye nemingxuma).
Imigangatho emibini eyongeziweyo ye-WS2 yongezwa ukunyusa amandla onke e-oscillator kwaye ngoko ke ukuvelisa ngokucacileyo ukwahlula kweRabi kumazwe e-polariton.
Indlela yokusebenza ye-resonator ihlengahlengiswa ngokuguqula ubukhulu be-PMMA layer (i-polymethyl methacrylate, oko kukuthi i-plexiglass).
Umfanekiso 1b Lo ngumfanekiso omfutshane we-vdW heterostructure kumphezulu we-Bragg reflector esasaziweyo. Ngenxa yokukhanya okuphezulu kwesibonisi seBragg esisasaziweyo, esingumaleko ongezantsi, indawo yetonela emfanekisweni inomahluko osezantsi kakhulu wokubonisa, okukhokelela ekubonweni kuphela umaleko oshinyeneyo ophezulu we-hBN.
Igrafu 1s ngumzobo wezowuni ye-vdW ye-heterostructure kwi-tunnel geometry phantsi kokufuduswa. I-Electroluminescence (EL) ibonwa ngaphezu kwe-voltage ye-threshold xa inqanaba le-Fermi eliphezulu (ezantsi) igraphene iguqulwa ngasentla (ngezantsi) ibhendi ye-conduction (valence) ye-WS2, ivumela i-electron (umngxuma) ukuba itonele kwi-conduction (valence) Iqela le-WS2. Oku kudala iimeko ezifanelekileyo zokuyilwa kwee-excitons kwi-WS2 layer kunye ne-radiative (radiative) yokudibanisa i-electron-hole elandelayo.
Ngokungafani ne-pn junction light emitters, efuna i-doping ukuba isebenze, i-EL esuka kwizixhobo ze-tunnel ixhomekeke kuphela kwi-tunnel yangoku, ukuphepha ukulahlekelwa kwe-optical kunye naluphi na utshintsho kwi-resistantivity ebangelwa utshintsho lweqondo lokushisa. Kwangaxeshanye, ulwakhiwo lwetonela luvumela indawo yokukhupha enkulu kakhulu xa kuthelekiswa nezixhobo ze-dichalcogenide ezisekelwe kwi-pn junctions.
Umfanekiso 1d ibonisa iimpawu zombane zoxinaniso lwangoku lwetonela (J) njengomsebenzi wombane ocalanye (V) phakathi kwee-electrode zegraphene. Ukunyuka okubukhali kwamandla ombane afanelekileyo kunye nokungalunganga kubonisa ukwenzeka kwe-tunnel current ngokusebenzisa isakhiwo. Kwinqanaba eliphezulu leeleya ze-hBN (~ 2 nm), umsinga obalulekileyo wokuhamba kunye nokwanda kwexesha lokuphila kwabathwali abafakwe kwi-radiative recombination.
Ngaphambi kokuba kuqhutywe uvavanyo lwe-electroluminescence, isixhobo sasibonakaliswe nge-angle-resolved white light reflectance ukuqinisekisa ubukho be-excitonic coupling enamandla.
Umfanekiso #2
Kumfanekiso 2 I-Angle-resolved reflectance spectra evela kummandla osebenzayo wesixhobo ibonisiwe, ibonisa ukuziphatha okuchasayo ukuwela. I-Photoluminescence (PL) nayo yabonwa phantsi kwe-excitation engaguqukiyo (460 nm), ibonisa ukukhutshwa okukhulu kwisebe elisezantsi le-polariton kunye nokukhutshwa okubuthathaka okuvela kwisebe eliphezulu le-polariton (2b).
phezu 2s ibonisa ukusasazwa kwe-polariton electroluminescence ngesantya sokutofa kwe-0.1 μA/μm2. Ukwahlulwa kweRabi kunye nokwahlulwa kwecango efunyenwe ngokufaka iindlela ze-oscillator (umgca oqinileyo nomhlophe odayiweyo) kumfuniselo we-EL yi-～33 meV kunye ～-13 meV, ngokulandelelanayo. Ukwahlulwa komngxuma kuchazwa njengo-δ = Ec − Ex, apho i-Ex ingamandla e-exciton kwaye i-Ec ichaza i-in-plane i-zero-momentum cavity emngxunyeni wamandla ephoton. Ishedyuli 2d Oku kunqunyulwa kwii-engile ezahlukeneyo ukusuka kwi-electroluminescent dispersion. Apha, ukusasazwa kweendlela eziphezulu kunye nezisezantsi ze-polariton kunye ne-anticrossing eyenzekayo kwindawo ye-exciton resonance ibonakala ngokucacileyo.
Umfanekiso #3
Njengoko i-tunneling yangoku isanda, ubukhulu be-EL buyanda. I-EL ebuthathaka evela kwi-polaritons ijongwa kufutshane ne-threshold shift (3), ngelixa kwindawo enkulu ngokwaneleyo yokufuduka ngaphezu komda, ukukhutshwa kwe-polariton kuyahluka (3b).
Kumfanekiso 3s ibonisa iploti yepolar ye-EL intensity njengomsebenzi we-engile, ebonisa i-cone yokukhutshwa emxinwa ye-±15 °. Ipateni yokusasazeka kwemitha ihlala ingatshintshanga kuzo zombini ezona zincinci (igophe eliluhlaza) kunye nobuninzi (igophe eliorenji) lovuselelo lwangoku. Vula 3d ibonisa ugxininiso oludityanisiweyo lwemisinga yetonela eyahlukeneyo ehambayo, ethi, njengoko inokubonwa kwigrafu, inomgca kakhulu. Ke ngoko, ukonyusa langoku ukuya kumaxabiso aphezulu kunokukhokelela ekusasazweni ngempumelelo kwee-polaritons ecaleni kwesebe elisezantsi kunye nokudala iphethini yokukhupha emxinwa kakhulu ngenxa yesizukulwana se-polariton. Nangona kunjalo, kolu vavanyo kwakungenakwenzeka ukufezekisa oku ngenxa yokunciphisa okuhambelana nokuchithwa kwe-dielectric yesithintelo setonela ye-hBN.
Amachaphaza abomvu avuliwe 3d bonisa imilinganiselo yesinye isalathisi - sangaphandle ukusebenza kakuhle kwequantum*.
Ukusebenza kweQuantum* - umlinganiselo wenani leefotoni, ukuxutywa okubangele ukubunjwa kwee-quasiparticles, kwinani elipheleleyo leefotoni ezixutywe.
Ukusebenza kwe-quantum ephawulweyo kuthelekiswa naleyo kwezinye ii-LED ze-polariton (ezisekelwe kwizinto eziphilayo, iityhubhu zekhabhoni, njl.). Kuyafaneleka ukuba uqaphele ukuba kwisixhobo esiphantsi kophando ubukhulu bokukhanya okukhupha ukukhanya kuphela ngu-0.7 nm, ngelixa kwezinye izixhobo eli xabiso liphezulu kakhulu. Iingcali zenzululwazi azifihli ukuba ukusebenza kwe-quantum yesixhobo sabo akukona kuphezulu, kodwa kunokunyuswa ngokubeka inani elikhulu le-monolayers ngaphakathi kwendawo ye-tunnel, ehlulwe ngamanqwanqwa amancinci e-hBN.
Abaphandi baye bavavanya umphumo we-resonator detuning kwi-polariton EL ngokwenza esinye isixhobo, kodwa nge-detuning enamandla (-43 meV).
Umfanekiso #4
Kumfanekiso 4 I-EL spectra enesisombululo se-angular yeso sixhobo siboniswa kwi-xinano yangoku ye-0.2 μA/μm2. Ngenxa ye-detuning eyomeleleyo, isixhobo sibonisa umphumo ochaziweyo we-bottleneck kwi-EL kunye nokukhutshwa okuphezulu okwenzeka kwi-angle enkulu. Oku kuqinisekiswa ngakumbi kumfanekiso 4b, apho iigrafu ezimhlophe zesi sixhobo zithelekiswa neyokuqala (2s).
Ukuze ufumane ulwazi oluthe kratya malunga nee-nuances zophononongo, ndincoma ukujonga .
Ipilo
Ngaloo ndlela, zonke iingqalelo kunye nemilinganiselo echazwe ngasentla iqinisekisa ubukho be-polariton electroluminescence kwi-vdW heterostructure eyakhelwe kwi-microcavity optical. Uyilo lwe-tunnel yesixhobo esiphantsi kophando luqinisekisa ukuqaliswa kwee-electron / imingxuma kunye nokudityaniswa kwakhona kwi-WS2 monolayer, esebenza njenge-emitter yokukhanya. Kubalulekile ukuba indlela yetonela yesixhobo ayifuni i-alloying yamacandelo, enciphisa ilahleko kunye neenguqu ezahlukeneyo ezinxulumene nobushushu.
Kwafunyaniswa ukuba i-EL ine-directivity ephezulu ngenxa yokusabalalisa i-resonator. Ke ngoko, ukuphucula umgangatho womgangatho wecavity kunye nokuhanjiswa okuphezulu kwangoku kuya kuphucula ukusebenza kakuhle kwe-microcavity LEDs, kunye ne-microcavity polaritons elawulwa ngombane kunye ne-photonic lasers.
Lo msebenzi waphinda waqinisekisa ukuba i-dichalcogenides yesinyithi yenguqu ineempawu ezizodwa kunye noluhlu olubanzi kakhulu lwezicelo.
Uphando olunjalo kunye nokuveliswa kwezinto ezintsha kunokuphembelela kakhulu uphuhliso kunye nokusasazeka kobuchwephesha bokuhanjiswa kwedatha usebenzisa ii-LED kunye nokukhanya ngokwayo. Ubuchwephesha obunjalo bexesha elizayo bubandakanya i-Li-Fi, enokubonelela ngesantya esiphezulu kakhulu kune-Wi-Fi ekhoyo ngoku.
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