Shekaru da yawa, masana kimiyya daga ko'ina cikin duniya suna yin abubuwa biyu - ƙirƙira da haɓakawa. Kuma wani lokacin ba a bayyana wanne ne ya fi wahala ba. Ɗauka, alal misali, LEDs na yau da kullum, waɗanda suke kama da sauƙi kuma na yau da kullum a gare mu cewa ba mu kula da su ba. Amma idan kun ƙara wasu abubuwan haɓakawa, ɗanɗano na polaritons da tungsten disulfide don dandana, LEDs ba za su ƙara zama masu fa'ida ba. Duk waɗannan sharuɗɗan abstruse sunaye ne na abubuwan da ba a saba gani ba, wanda haɗuwarsu ya ba wa masana kimiyya daga Kwalejin City ta New York damar ƙirƙirar sabon tsarin da zai iya watsa bayanai cikin sauri ta amfani da haske. Wannan ci gaban zai taimaka inganta fasahar Li-Fi. Menene ainihin sinadaran sabuwar fasahar da aka yi amfani da su, menene girke-girke na wannan "tasa" kuma menene ingancin sabon LED exciton-polariton? Rahoton masana kimiyya zai gaya mana game da wannan. Tafi
Tushen bincike
Idan komai ya sauƙaƙa zuwa kalma ɗaya, to wannan fasaha mai haske ce kuma duk abin da ke da alaƙa da ita. Na farko, polaritons, wanda ke tasowa lokacin da photons ke hulɗa tare da matsakaiciyar motsa jiki (phonons, excitons, plasmons, magnons, da dai sauransu). Abu na biyu, abubuwan haɓakawa sune haɓakar lantarki a cikin dielectric, semiconductor ko ƙarfe, ƙaura ta cikin crystal kuma ba su da alaƙa da canja wurin cajin lantarki da taro.
Yana da mahimmanci a lura cewa waɗannan ƙananan ƙwayoyin cuta suna son sanyi sosai; Ana iya lura da ayyukansu kawai a cikin ƙananan yanayin zafi, wanda ke iyakance aikace-aikacen su sosai. Amma a da. A cikin wannan aikin, masana kimiyya sun sami damar shawo kan ƙarancin zafin jiki kuma suna amfani da su a yanayin zafi.
Babban fasalin polaritons shine ikon ɗaure photons da juna. Photons suna karo da rubidium atom suna samun taro. A cikin ci karo da yawa, photons suna billa juna, amma a lokuta da yawa suna samar da nau'i-nau'i da uku, yayin da suke rasa bangaren atomic da rubidium atom ke wakilta.
Amma don yin wani abu da hasken, dole ne a kama shi. Don wannan, ana buƙatar resonator na gani, wanda shine haɗuwa da abubuwa masu haske waɗanda ke samar da igiyar haske a tsaye.
A cikin wannan binciken, har ma da abubuwan da ba a saba gani ba, exciton-polaritons, waɗanda aka samo su saboda ƙaƙƙarfan haɗakarwa na excitons da photon da aka makale a cikin rami na gani, suna taka muhimmiyar rawa.
Duk da haka, wannan bai isa ba, saboda tushen kayan abu ya zama dole, don yin magana. Kuma wanda, idan ba canjin ƙarfe dichalcogenide (TDM), zai taka wannan rawar fiye da sauran. Don zama madaidaici, an yi amfani da monolayer na WS2 (tungsten disulfide) azaman kayan fitarwa, wanda ke da kuzari mai ɗaure mai ban sha'awa, wanda ya zama ɗaya daga cikin manyan ma'auni don zaɓar tushen kayan.
Haɗin duk abubuwan da aka kwatanta a sama sun ba da damar ƙirƙirar LED na polariton mai sarrafa wutar lantarki da ke aiki a zafin jiki.
Don aiwatar da wannan na'urar, WS2 monolayer yana tsakanin siraran hexagonal boron nitride (hBN) shinge shinge tare da yadudduka na graphene suna aiki azaman lantarki.
Sakamakon bincike
WS2, kasancewar dichalcogenide karfen canji, kuma siriri ne na van der Waals (vdW). Wannan yana nuna kaddarorin sa na lantarki, na gani, injina da kuma thermal Properties.
A hade tare da wasu kayan vdW, irin su graphene (a matsayin mai gudanarwa) da boron nitride hexagonal (hBN, a matsayin insulator), ana iya gane nau'ikan na'urorin semiconductor iri-iri, waɗanda suka haɗa da LEDs. Irin wannan haɗuwa na kayan van der Waals da polaritons an riga an gano su a baya, kamar yadda masu binciken suka bayyana a fili. Duk da haka, a cikin rubuce-rubucen da suka gabata, tsarin da aka haifar sun kasance masu rikitarwa kuma marasa kyau, kuma ba su bayyana cikakken damar kowane ɗayan sassan ba.
Ɗaya daga cikin ra'ayoyin da magabata suka yi wahayi zuwa gare shi shine amfani da dandamali na kayan abu mai fuska biyu. A wannan yanayin, yana yiwuwa a aiwatar da na'urori tare da yadudduka na siraran atomically waɗanda za a iya haɗa su tare da wasu kayan vdW waɗanda ke aiki azaman lambobin sadarwa (graphene) da shingen tunneling (hBN). Bugu da ƙari, wannan nau'i-nau'i biyu ya sa ya yiwu a haɗa LEDs na polariton tare da kayan vdW tare da abubuwan da ba a saba da su ba, ƙaƙƙarfan ƙarfin hali, da / ko canja wurin topological mara kyau. A sakamakon irin wannan haɗuwa, za ku iya samun sabon nau'in na'urar gaba ɗaya, wanda kaddarorin na iya zama sabon abu. Amma, kamar yadda masana kimiyya suka ce, wannan batu ne na wani binciken.
Hoto #1
Akan hoton 1 yana nuna nau'in nau'in nau'in nau'in nau'in nau'in nau'in nau'in nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i nau'i) wanda ya yi kama da kek. Mudubi na sama na resonator na gani shine Layer na azurfa, kuma na ƙasa shine Layer Layer 12 da aka rarraba. Bragg reflector*. Akwai yankin rami a cikin yanki mai aiki.
Rarraba Bragg Reflector* - tsarin da yawa yadudduka, a cikin abin da refractive index na abu lokaci-lokaci canza perpendicular zuwa yadudduka.
Yankin rami ya ƙunshi tsarin vdW wanda ya ƙunshi WS2 monolayer (hasken haske), siraran hBN yadudduka a ɓangarorin monolayer ( shingen rami) da graphene (electrodes masu haske don gabatarwar electrons da ramuka).
An ƙara ƙarin yadudduka na WS2 guda biyu don ƙara ƙarfin juzu'i na oscillator don haka a sami ƙarin fa'ida Rabin rabuwar jihohin polariton.
Ana kunna yanayin aiki na resonator ta hanyar canza kauri na Layer PMMA (polymethyl methacrylate, i.e. plexiglass).
Hoto 1b wannan hoto ne na tsarin tsarin vdW akan saman da aka rarraba Bragg reflector. Saboda babban abin haskakawa na Bragg reflector wanda aka rarraba, wanda shine Layer na ƙasa, yankin ramin da ke cikin hoton yana da ƙarancin juzu'i, sakamakon haka kawai ana lura da babban kauri na hBN.
Shafi 1s yana wakiltar zane-zane na yanki na vdW heterostructure a cikin joometry na rami a ƙarƙashin ƙaura. Ana lura da Electroluminescence (EL) sama da ƙarfin ƙarfin kofa lokacin da matakin Fermi na sama (ƙananan) graphene ya motsa sama (a ƙasa) ƙungiyar WS2 conduction (valence), ƙyale electron (rami) zuwa rami cikin WS2 conduction (valence) band. Wannan yana haifar da kyawawan yanayi don samuwar excitons a cikin WS2 Layer wanda ke biye da radiyo (radiative) recombination electron-rami.
Ba kamar masu fitar da haske ba dangane da pn junctions, waɗanda ke buƙatar doping don aiki, EL daga na'urorin rami ya dogara ne kawai akan ramin halin yanzu, wanda ke guje wa asarar gani da duk wani canje-canje na juriya da canjin yanayi ya haifar. A lokaci guda, tsarin gine-ginen ramin yana ba da damar yanki mafi girma na radiation idan aka kwatanta da na'urorin dichalcogenide bisa pn junctions.
Hoto 1d yana nuna halayen wutar lantarki na yawan ɗigon tunneling na yanzu (J) a matsayin aikin bias voltage (V) tsakanin graphene lantarki. Ƙaƙƙarfan haɓakawa a halin yanzu don ingantaccen ƙarfin lantarki da mara kyau yana nuna abin da ya faru na ramin yanzu ta hanyar tsarin. A mafi kyawun kauri na yadudduka na hBN (~ 2 nm), ana lura da ƙaƙƙarfan ramin tunnel ɗin yanzu da haɓaka tsawon rayuwar masu ɗaukar hoto don sake haɗawa mai haske.
Kafin gwajin electroluminescence, na'urar tana da siffa ta farin haske mai haske tare da ƙudurin kusurwa don tabbatar da kasancewar ƙaƙƙarfan ɗaurin exciton.
Hoto #2
Akan hoton 2 Ana nuna bakan haske mai warware kusurwa daga yankin da ke aiki na na'urar, yana nuna halayen hana hayewa. An kuma lura da Photoluminescence (PL) tare da tashin hankali mara ƙarfi (460 nm), yana nuna ƙaƙƙarfan fitarwa daga reshe na polariton da rauni mai rauni daga reshe na sama na polariton.2b).
a kan 2s Ana nuna watsawar wutar lantarki na polariton don shigar da 0.1 μA/μm2. Ragewar Rabi da tsinkayar resonator da aka samu ta hanyar dacewa da yanayin oscillator (tsararriyar layin fari mai dige-dige) zuwa gwajin lantarki shine 33 meV da ～-13 meV, bi da bi. An bayyana ƙaddamar da resonator a matsayin δ = Ec - Ex, inda Ex shine makamashin exciton kuma Ec shine makamashin resonator na photon tare da sifili a cikin jirgin sama. Jadawalin 2d yanke ne a kusurwoyi daban-daban daga watsawar wutar lantarki. Anan mutum zai iya ganin tarwatsewar hanyoyin polariton na sama da na ƙasa tare da anticrossing da ke faruwa a yankin resonance na exciton.
Hoto #3
Yayin da yanayin tunnel ɗin ke ƙaruwa, jimlar ƙarfin EL yana ƙaruwa. EL mai rauni daga polaritons ana lura da shi kusa da son zuciya (3), yayin da a isasshe babban motsi sama da bakin kofa, watsin polariton ya zama dabam (3b).
Akan hoton 3s yana nuna madaidaicin jadawali na ƙarfin EL azaman aikin kwana, yana nuna ƙunƙunwar mazugi na ± 15°. Tsarin radiation ya kasance a zahiri baya canzawa don duka mafi ƙarancin (koren lanƙwasa) da matsakaicin (madaidaicin lanƙwan orange). Kunna 3d An nuna ƙarfin haɗin kai don magudanar ruwa masu motsi daban-daban, waɗanda, kamar yadda ake iya gani daga jadawali, madaidaiciya. Sabili da haka, haɓaka halin yanzu zuwa manyan dabi'u na iya haifar da nasarar watsawar polaritons tare da ƙananan reshe da ƙirƙirar yanayin kunkuntar radiyo saboda haɓakar polaritons. Koyaya, a cikin wannan gwaji, wannan bai yuwu ba saboda ƙayyadaddun da ke tattare da rushewar shingen rami na hBN.
jajayen dige akan 3d nuna ma'auni na wani mai nuna alama - waje yadda ya dace*.
Ƙimar Ƙimar Ƙimar* shine rabon adadin photons wanda shayewar su ya haifar da samuwar kwayoyin halitta zuwa yawan adadin photon da aka sha.
Ƙwararren ƙididdigewa da aka lura yana daidai da wancan a cikin sauran LEDs na polariton (dangane da kayan halitta, tubes carbon, da dai sauransu). Ya kamata a lura cewa kauri daga cikin na'urar da ke fitar da haske a cikin na'urar da ake nazarin shine kawai 0.7 nm, yayin da a wasu na'urori wannan darajar ta fi girma. Masana kimiyya ba sa ɓoye gaskiyar cewa ƙimar ingancin na'urar su ba ita ce mafi girma ba, amma ana iya haɓaka ta ta hanyar sanya adadin monolayers mafi girma a cikin yankin ramin, wanda ya rabu da ƙananan yadudduka na hBN.
Masu binciken sun kuma gwada tasirin resonator detuning a kan polariton EL ta hanyar yin wata na'ura, amma tare da ƙaddamarwa mai ƙarfi (-43 meV).
Hoto #4
Akan hoton 4 Ana nuna baƙaƙen EL tare da ƙudurin kusurwa na irin wannan na'urar a ƙimar yanzu na 0.2 μA/μm2. Saboda ƙaƙƙarfan fiddawa, na'urar tana nuna tasirin ƙwanƙwasa bayyananne a cikin EL tare da mafi girman fitar da ke faruwa a babban kusurwa. An kara tabbatar da hakan a cikin hoton. 4b, inda aka kwatanta filayen polar na wannan na'ura da na farko (2s).
Don ƙarin cikakken sani tare da nuances na binciken, Ina ba da shawarar dubawa .
Epilogue
Don haka, duk abubuwan lura da ma'auni da aka kwatanta a sama suna tabbatar da kasancewar polariton electroluminescence a cikin tsarin heterostructure na vdW wanda aka saka a cikin ƙaramin ƙaramin gani. Gine-ginen rami na na'urar da ke ƙarƙashin binciken yana tabbatar da ƙaddamar da electrons/ramuka da sake haɗuwa a cikin WS2 monolayer, wanda ke aiki a matsayin mai fitar da haske. Yana da mahimmanci cewa tsarin rami na na'urar baya buƙatar haɗaɗɗen abubuwan haɗin gwiwa, wanda ke rage asara da canje-canje masu alaƙa da zafin jiki daban-daban.
An gano cewa EL yana da babban jagora saboda watsawar resonator. Saboda haka, inganta ingancin factor na resonator da mafi girma halin yanzu wadata zai inganta yadda ya dace na microcavity LEDs, kazalika da lantarki sarrafa microcavity polaritons da photon Laser.
Wannan aikin ya sake tabbatar da cewa canjin ƙarfe dichalcogenides yana da ƙayyadaddun kaddarorin gaske da kewayon aikace-aikace.
Irin wannan bincike da ƙirƙira ƙirƙira na iya yin tasiri sosai ga haɓakawa da yada fasahohin watsa bayanai ta hanyar LED da hasken kanta. Irin waɗannan fasahohin na gaba sun haɗa da Li-Fi, wanda zai iya samar da saurin sauri fiye da Wi-Fi da ake da shi a yanzu.
Na gode da hankalin ku, ku kasance da sha'awar kuma ku sami mako mai kyau kowa da kowa! 🙂
Na gode da kasancewa tare da mu. Kuna son labaran mu? Kuna son ganin ƙarin abun ciki mai ban sha'awa? Goyon bayan mu ta hanyar ba da oda ko ba da shawara ga abokai, Rangwamen 30% ga masu amfani da Habr akan keɓaɓɓen analogue na sabar matakin shigarwa, wanda mu muka ƙirƙira muku: (akwai tare da RAID1 da RAID10, har zuwa 24 cores kuma har zuwa 40GB DDR4).
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source: www.habr.com