Kwemakore akawanda, masayendisiti kubva kumativi ose enyika ave achiita zvinhu zviviri - kugadzira nekuvandudza. Uye dzimwe nguva hazvisi pachena kuti ndezvipi zvakanyanya kuoma. Tora, semuenzaniso, maLED akajairwa, anoita seakareruka uye akajairika kwatiri zvekuti isu hatitomboatarisire. Asi kana iwe ukawedzera maexcitons mashoma, pini ye polaritons uye tungsten disulfide kuravira, ma LED haachazove prosaic. Ese aya mazwi abstruse mazita ezvimiro zvisina kujairika zvakanyanya, musanganiswa wakabvumira masayendisiti kubva kuCity College yeNew York kugadzira hurongwa hutsva hunokwanisa kufambisa ruzivo nekukurumidza zvakanyanya vachishandisa chiedza. Iyi budiriro ichabatsira kuvandudza tekinoroji yeLi-Fi. Ndezvipi zvakashandiswa zvehunyanzvi hutsva zvakashandiswa, ndeipi nzira yeiyi "ndiro" uye chii chiri kushanda kweiyo itsva exciton-polariton LED? Mushumo wemasayendisiti uchatiudza nezveizvi. Enda.
Hwaro hwechidzidzo
Kana isu tichirerutsa zvese kusvika kune rimwe izwi, saka tekinoroji iyi yakareruka uye zvese zvakabatana nazvo. Chekutanga, polaritons, iyo inomuka kana mafotoni achibatana nekunakidzwa kwepakati (phonon, excitons, plasmons, magnons, nezvimwewo). Chechipiri, maexcitons emagetsi ekuwedzera mune dielectric, semiconductor kana simbi inotama mukati mekristaro uye haina hukama nekufambiswa kwechaji yemagetsi uye huwandu.
Izvo zvakakosha kuti uzive kuti aya ma quasiparticles anoda kutonhora zvakanyanya, i.e. Basa ravo rinogona kungoonekwa chete pamatembiricha akadzika kwazvo, izvo zvinoganhurira zvakanyanya kushanda kwavo. Asi izvozvo zvaiva kare. Mubasa iri, masayendisiti akakwanisa kukunda kudzikamisa tembiricha uye kuvashandisa patembiricha yemumba.
Chinhu chikuru chepolaritoni ndiko kukwanisa kusunga mafotoni pamwe chete. Mapikicha anodhumhana nemaatomu erubidium anowana huwandu. Mukuita kudhumhana kwakadzokororwa, mafotoni anobvondomoka kubva kune mumwe, asi muzviitiko zvisingawanzoiti anoita maviri maviri uye matatu, achirasikirwa nechikamu cheatomu chinomiririrwa neatomu rerubidium.
Asi kuita chimwe chinhu nechiedza, unofanira kuchibata. Nokuda kweizvi, optical resonator inodiwa, inova seti yezvinhu zvinoratidzira zvinoumba chiedza chakamira.
Muchidzidzo ichi, basa rakakosha rinoitwa neakanyanya kujairika quasiparticles - exciton-polaritons, iyo inoumbwa nekuda kwekubatana kwakasimba kweiyo excitons uye mafoto akavharirwa mune optical cavity.
Zvisinei, izvi hazvina kukwana, nokuti hwaro hwokunyama hunodiwa, sokunge zvakadaro. Uye ndiani ari nani kupfuura shanduko yesimbi dichalcogenide (TMD) achaita basa iri? Kunyanya, iyo WS2 (tungsten disulfide) monolayer yakashandiswa sechinhu chinoburitsa, ine inonakidza exciton inosunga simba, iyo yakava imwe yenzira huru yekusarudza hwaro hwezvinhu.
Iko kusanganiswa kwezvinhu zvese zvinotsanangurwa pamusoro apa kwakaita kuti zvikwanise kugadzira iyo yemagetsi inodzorwa polariton LED inoshanda pakamuri tembiricha.
Kuti uone chishandiso ichi, monolayer yeWS2 inoiswa pakati peyakaonda hexagonal boron nitride (hBN) tunnel zvipingamupinyi zvine graphene layer ichiita semagetsi.
Mhedzisiro yekutsvaga
WS2, iri shanduko yesimbi dichalcogenide, zvakare iri atomu yakatetepa van der Waals (vdW) zvinhu. Izvi zvinotaura nezvezvakasiyana zvemagetsi, optical, mechanical uye thermal properties.
Mukubatana nezvimwe zvinhu zvevdW, senge graphene (se conductor) uye hexagonal boron nitride (hBN, se insulator), huwandu hwese hwemagetsi anodzorwa semiconductor zvishandiso, izvo zvinosanganisira LEDs, zvinogona kuitika. Musanganiswa wakafanana wevan der Waals zvinhu uye polaritons zvakatoitika kare, sekutaura kunoita vaongorori pachena. Zvisinei, mumabasa ekare, maitiro akaguma akanga akaoma uye asina kukwana, uye haana kuratidza kukwanisa kwakakwana kwechikamu chimwe nechimwe.
Imwe yemafungiro akafemerwa nevakatangira yaive yekushandiswa kwenzvimbo ine mativi maviri. Muchiitiko ichi, zvinogoneka kuona zvishandiso zvine maatomu akatetepa emissive layers, ayo anogona kubatanidzwa nezvimwe vdW zvinhu zvinoita sevanobatika (graphene) uye tunnel zvipingamupinyi (hBN). Pamusoro pezvo, mbiri-dimensionality yakadaro inoita kuti zvikwanise kusanganisa ma LED epolariton nevdW zvinhu zvine zvimiro zvemagineti zvisina kujairika, yakasimba superconductivity uye/kana isiri-standard topological transfers. Somugumisiro wekubatanidzwa kwakadaro, rudzi rutsva rwechigadzirwa runogona kuwanikwa, izvo zvingave zvisingawanzoitiki. Asi, sekutaura kunoita masayendisiti, iyi inyaya yeimwe chidzidzo.
Mufananidzo #1
Mumufananidzo 1a inoratidza matatu-dimensional modhi yemudziyo wakafanana nekeke rakaturikidzana. Girazi repamusoro reonator resonator ira resirivha, uye girazi rezasi rine 12-layer yakagoverwa. Bragg reflector*. Nzvimbo inoshanda ine tunnel zone.
Yakaparadzirwa Bragg reflector* - chimiro chezvikamu zvakawanda umo iyo refractive index yezvinyorwa nguva nenguva inoshandura perpendicular kune zvidimbu.
Iyo tunnel zone ine vdW heterostructure inoumbwa neWS2 monolayer (light emitter), zvidimbu zvitete zvehBN kumativi ese e monolayer (tunnel barrier) uye graphene (transparent electrodes yekusuma maerekitironi nemaburi).
Mamwe maviri akaturikidzana eWS2 akawedzerwa kuti awedzere simba rose reiyo oscillator uye nekudaro kuburitsa yakawedzera kududzirwa Rabi kupatsanura kwenzvimbo dzepolariton.
Nzira yekushanda ye resonator inogadziriswa nekushandura kukora kwePMMA layer (polymethyl methacrylate, i.e. plexiglass).
Image Image 1b Ichi chifananidzo chevdW heterostructure pamusoro peiyo yakagoverwa Bragg reflector. Nekuda kwekutarisisa kwepamusoro kweiyo Bragg reflector yakagoverwa, inova chikamu chepasi, iyo tunnel zone mumufananidzo ine yakaderera zvakanyanya kuratidza musiyano, zvichikonzera chete iyo yepamusoro gobvu hBN layer inoonekwa.
Girafu 1s ndiyo vdW zone dhayagiramu yeheterostructure mugeometry yetunnel pasi pekudzingwa. Electroluminescence (EL) inocherechedzwa pamusoro pechikumbaridzo magetsi apo Fermi level yekumusoro (pasi) graphene inotamiswa pamusoro (pazasi) conduction (valence) bhendi reWS2, ichibvumira electron (gomba) kuti ipinde mu conduction (valence) bhendi reWS2. Izvi zvinogadzira mamiriro akanaka ekugadzirwa kwemaexcitons muWS2 layer ine inotevera radiative (radiative) electron-hole recombination.
Kusiyana nepn junction light emitters, iyo inoda kuti doping ishande, EL kubva kune tunnel madivayiri inoenderana chete neiyo tunnel ikozvino, kudzivirira kurasikirwa kwemaziso uye chero shanduko muresistivity inokonzerwa nekushanduka kwekushisa. Panguva imwecheteyo, dhizaini yedhizaini inobvumira nzvimbo yakakura kwazvo yekuburitsa kana ichienzaniswa nedhichalcogenide zvishandiso zvinoenderana nepn junctions.
Image Image 1d inoratidza maitiro emagetsi eiyo tunneling ikozvino density (J) sekushanda kwe bias voltage (V) pakati pegraphene electrodes. Kuwedzera kwakanyanya kwezvino kune ese akanaka uye asina kunaka voltages kunoratidza kuitika kwe tunneling ikozvino kuburikidza nechimiro. Pakunyanya kukora kwehBN layers (~ 2 nm), yakakosha tunneling ikozvino uye kuwedzera kwehupenyu hwevakamisikidzwa vatakuri veradiative recombination inoonekwa.
Asati aita kuyedza kwe electroluminescence, mudziyo uyu wairatidzwa nekona-yakagadziriswa chena mwenje kuratidza kuratidza kuvepo kweiyo yakasimba excitonic coupling.
Mufananidzo #2
Mumufananidzo 2a Angle-resolved reflectance spectra kubva munzvimbo inoshanda yechigadzirwa inoratidzwa, ichiratidza maitiro ekurwisa-kuyambuka. Photoluminescence (PL) yakaonekwawo pasi pekunakidzwa kusingadzokeri (460 nm), ichiratidza kubuda kwakanyanya kubva kubazi rezasi repolariton uye kuburitsa kusina simba kubva kubazi repamusoro repolariton.2b).
pamusoro 2s inoratidza kupararira kwepolariton electroluminescence pajekiseni re 0.1 ΞΌA/ΞΌm2. Iyo Rabi kupatsanura uye mhango detuning inowanikwa nekukodzera maoscillator modes (yakasimba uye yakatsetseka chena mutsara) kune EL kuyedza i ο½33 meV uye ο½-13 meV, zvichiteerana. The cavity detuning inotsanangurwa se Ξ΄ = Ec β Ex, apo Ex ndiyo exciton simba uye Ec inoreva in-ndege zero-momentum cavity photon simba. Purogiramu 2d Uku kuchekwa pamakona akasiyana kubva pakupararira kwe electroluminescent. Pano, kupararira kwepamusoro uye pasi polaritoni modes ine anticrossing inoitika munzvimbo yeexciton resonance inoonekwa zvakajeka.
Mufananidzo #3
Sezvo iyo tunneling ikozvino inowedzera, iyo yakazara EL intensity inowedzera. Weak EL kubva polaritons inoonekwa padyo nechikumbaridzo chekuchinja (3a), pavanenge vakakura zvakakwana pamusoro pechikumbaridzo, polariton emission inova yakasiyana (3b).
Mumufananidzo 3s inoratidza polar plot ye EL intensity sebasa rekona, rinoratidza koni yakamanikana ye Β± 15 Β°. Iyo radiation pateni inoramba isina kuchinjika kune ese ari maviri mashoma (girinhi curve) uye yepamusoro (orenji curve) excitation current. On 3d inoratidza kusimba kwakabatanidzwa kweakasiyana siyana anofamba mugero, ayo, sezvingaonekwa kubva pagirafu, ane mutsara chaiwo. Naizvozvo, kuwedzera ikozvino kune yakakwirira hunhu kunogona kutungamira mukupararira kwakabudirira kwepolaritoni padivi pebazi rezasi uye kugadzira yakatetepa emission pateni nekuda kwechizvarwa chepolarton. Nekudaro, mukuyedza uku hazvina kukwanisa kuita izvi nekuda kwekuganhurwa kwakabatana nekuparara kwedielectric yehBN tunnel barriers.
Madonhwe matsvuku ari pamusoro 3d ratidza zviyero zvechimwe chiratidzo - chekunze quantum performance*.
Quantum kunyatsoita * - chiyero chenhamba yemafotoni, kubatwa kwacho kwakakonzera kuumbwa kwe quasiparticles, kusvika kuhuwandu hwemafotoni akabatwa.
Iko kucherechedzwa kwehuwandu hwehuwandu hunofananidzwa neiyo mune mamwe polaritoni LEDs (yakavakirwa pane organic zvinhu, kabhobhu machubhu, nezvimwewo). Zvakakosha kucherechedza kuti mumudziyo uri pasi pechidzidzo, ukobvu hwemwenje-emitting layer inongova 0.7 nm, nepo mune mamwe maturusi kukosha uku kwakakwira zvakanyanya. Masayendisiti haavanze chokwadi chekuti kuwanda kwechigadzirwa chavo hakusi kwepamusoro-soro, asi kunogona kuwedzerwa nekuisa nhamba yakakura yemamonolayers mukati meiyo tunnel zone, yakaparadzaniswa nematehwe matete ehBN.
Vatsvakurudzi vakaedzawo mhedzisiro ye resonator detuning pa polariton EL nekugadzira imwe mudziyo, asi ine yakasimba detuning (-43 meV).
Mufananidzo #4
Mumufananidzo 4a EL spectra ine angular resolution yemudziyo wakadaro inoratidzwa pane yazvino density ye0.2 ΞΌA/ΞΌm2. Nekuda kweiyo yakasimba detuning, mudziyo unoratidza yakadudzwa bhodhoro mhedzisiro muEL neiyo emission yepamusoro inoitika pakona hombe. Izvi zvinosimbiswa zvakare mumufananidzo 4b, apo magirafu epolar echigadzirwa ichi anofananidzwa neyokutanga (2s).
Kuti uwane rumwe ruzivo rwakadzama rwema nuances echidzidzo, ini ndinokurudzira kutarisa .
Epilogue
Nokudaro, zvose zvinoonekwa uye zviyero zvinotsanangurwa pamusoro apa zvinosimbisa kuvapo kwepolarion electroluminescence mu vdW heterostructure yakavakwa mu optical microcavity. Mavakirwo etunnel yechishandiso chiri pasi pechidzidzo anovimbisa kuunzwa kwemaerekitironi/maburi uye kubatanidzwazve muWS2 monolayer, iyo inoshanda sechiedza emitter. Izvo zvakakosha kuti nzira yekugezera yechishandiso haidi kusanganiswa kwezvikamu, izvo zvinoderedza kurasikirwa uye kwakasiyana-siyana kunoenderana nekushisa.
Yakawanikwa kuti EL ine hutungamiri hwepamusoro nekuda kwekupararira kwe resonator. Naizvozvo, kuvandudza iyo cavity yemhando yechinhu uye yakakwira ikozvino kuendesa kunovandudza kugona kweiyo microcavity LEDs, pamwe nemagetsi anodzorwa microcavity polaritons uye photonic lasers.
Iri basa rakasimbisa zvakare kuti shanduko yesimbi dichalcogenides ine chaiyo yakasarudzika zvivakwa uye yakafaranuka kwazvo maapplication.
Tsvagiridzo yakadai uye zvigadzirwa zvitsva zvinogona kupesvedzera zvikuru kuvandudzwa uye kupararira kwetekinoroji yekufambisa data uchishandisa maLED uye chiedza pachacho. Tekinoroji dzakadaro dzemangwana dzinosanganisira Li-Fi, iyo inogona kupa zvakanyanya kumhanya kupfuura iripo ikozvino Wi-Fi.
Ndatenda nekuverenga, garai muchida kuziva uye muve nevhiki yakanaka vakomana! π
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