Abadlali abaningi emhlabeni jikelele abahlangabezane nenkathi ye-Xbox 360 bajwayelene kakhulu nesimo lapho ikhonsoli yabo iphenduka ipani lokuthosa ababengathosa kulo amaqanda. Isimo esidabukisayo esifanayo asenzeki kuphela ngama-consoles wegeyimu, kodwa namafoni, ama-laptops, amaphilisi nokunye okuningi. Eqinisweni, cishe noma iyiphi idivayisi ye-elekthronikhi ingathola ukushaqeka okushisayo, okungaholela hhayi kuphela ekuhlulekeni nasekucasuleni umnikazi wayo, kodwa futhi "ku-boom embi" yebhethri nokulimala okunzima. Namuhla sizojwayelana nocwaningo lapho ososayensi abavela eNyuvesi yaseStanford, njengo-Nick Fury ovela kumahlaya, benze isihlangu esivikela izingxenye ze-elekthronikhi ezingezwani nokushisa ekushiseni ngokweqile futhi, ngenxa yalokho, zivimbele ukuwohloka kwazo. Ososayensi bakwazi kanjani ukudala isihlangu esishisayo, yiziphi izingxenye zayo eziyinhloko futhi sisebenza kanjani? Sifunda ngalokhu nokunye okuningi embikweni weqembu locwaningo. Hamba.
Isisekelo socwaningo
Inkinga yokushisa ngokweqile yaziwa isikhathi eside kakhulu, futhi ososayensi bayixazulula ngezindlela ezihlukahlukene. Okunye okuthandwa kakhulu ukusetshenziswa kwengilazi, ipulasitiki ngisho nezingqimba zomoya, ezisebenza njengohlobo lwama-insulators emisebe eshisayo. Ezimweni ezingokoqobo zanamuhla, le ndlela ingathuthukiswa ngokunciphisa ukushuba kongqimba oluvikelayo kuma-athomu amaningana ngaphandle kokulahlekelwa izici zayo zokushisa ezishisayo. Yilokho kanye okwenziwa abacwaningi.
Yebo, sikhuluma ngama-nanomaterials. Kodwa-ke, ukusetshenziswa kwabo ekufakweni kwe-thermal ngaphambili kwakuyinkimbinkimbi yiqiniso lokuthi ubude be-wavelength bama-coolants (amaphononi*) mfushane kakhulu kunaleyo yama-electron noma ama-photon.
I-Phonon* - i-quasiparticle, okuyi-quantum yokunyakaza kokudlidliza kwama-athomu ekristalu.
Ngaphezu kwalokho, ngenxa yemvelo ye-bosonic yamaphononi, akunakwenzeka ukuwalawula nge-voltage (njengoba kwenziwa ngabathwali bokushaja), okwenza kube nzima ukulawula ukudluliswa kokushisa ezintweni eziqinile.
Ngaphambilini, izakhiwo ezishisayo zama-solids, njengoba abacwaningi besikhumbuza, zazilawulwa ngamafilimu e-nanolaminate nama-superlattices ngenxa yokuphazamiseka kwesakhiwo kanye nokuxhumana okuphezulu, noma nge-silicon ne-germanium nanowires ngenxa yokuhlakazeka kwe-phonon enamandla.
Eziningi zezindlela zokufaka ukushisa okushisayo ezichazwe ngenhla, ososayensi bakulungele ngokuzethemba ukukhomba izinto ezinezinhlangothi ezimbili, ubukhulu bazo obungeqi ama-athomu amaningana, okwenza kube lula ukulawula esikalini se-athomu. Esifundweni sabo basebenzisa van der Waals (vdW) ukuhlanganiswa kwezendlalelo ze-2D ezacile ze-athomu ukuze kuzuzwe ukumelana nokushisa okuphezulu kakhulu kuyo yonke i-heterostructure yazo.
Amabutho kaVan der Waals* — Amandla okusebenzelana ama-intermolecular/interatomic anamandla ayi-10-20 kJ/mol.
Indlela entsha yenza kwaba nokwenzeka ukuthola ukumelana nokushisa ku-vdW heterostructure enogqinsi oluyi-2 nm, uma kuqhathaniswa nolwelwesi lwe-SiO2 (i-silicon dioxide) enogqinsi lwama-300 nm.
Ngaphezu kwalokho, ukusetshenziswa kwe-vdW heterostructures kwenze kwaba nokwenzeka ukuthola ukulawula izakhiwo ezishisayo ezingeni le-athomu ngokusebenzisa ungqimba lwama-monolayers we-XNUMXD ahlukahlukene anobunzima be-athomu obuhlukene nezindlela zokudlidliza.
Ngakho-ke, masingadonsi amadevu ekati futhi ake siqale ukucabangela imiphumela yalolu cwaningo olumangalisayo.
Imiphumela yocwaningo
Okokuqala, ake sijwayelane nezici ze-microstructural kanye ne-optical ye-vdW heterostructures esetshenziswe kulolu cwaningo.
Isithombe #1
Esithombeni I-1 ikhombisa umdwebo ohlukanisayo we-heterostructure enezendlalelo ezine ehlanganisa (kusuka phezulu kuye phansi): i-graphene (Gr), i-MoSe2, i-MoS2, i-WSe22 kanye ne-SiO2/Si substrate. Ukuskena zonke izendlalelo ngesikhathi esisodwa, sebenzisa I-Raman laser* ngobude begagasi obungu-532 nm.
I-Raman laser* - uhlobo lwe-laser lapho indlela eyinhloko yokukhulisa ukukhanya i-Raman scattering.
URaman ehlakazeka, futhi, ukuhlakazeka kwe-inelastic kwemisebe ye-optical kuma-molecule ento, ehambisana noshintsho oluphawulekayo emithanjeni yemisebe.
Kusetshenziswe izindlela ezimbalwa ukuze kuqinisekiswe i-microstructural, thermal and electrical homogeneity ye-heterostructures: scanning transmission electron microscopy (STEM), photoluminescence spectroscopy (PL), Kelvin probe microscopy (KPM), scanning thermal microscopy (SThM), kanye neRaman spectroscopy kanye i-thermometry.
Isithombe 1b isibonisa i-Raman spectrum ye-Gr/MoSe2/MoS2/WSe22 heterostructure ku-substrate ye-SiO2/Si endaweni emakwe ngechashazi elibomvu. Lesi sakhiwo sibonisa isignesha ye-monolayer ngayinye ohlwini lwesendlalelo, kanye nesiginesha ye-Si substrate.
In 1c-1f Izithombe ze-STEM zenkundla emnyama ze-heterostructure ye-Gr/MoSe2/MoS2/WSe22 ziyaboniswa (1s) kanye ne-Gr/MoS2/WSe22 heterostructures (1d-1f) ngezimo ezihlukene ze-lattice. Izithombe ze-STEM zibonisa izikhala ze-vdW ezivala i-athomu ngaphandle kokungcoliswa, okuvumela ukushuba okuphelele kwalezi zakhiwo ze-heterostructures ukuthi zibonakale ngokugcwele. Ukuba khona kokuxhumanisa kwe-interlayer nakho kwaqinisekiswa ezindaweni ezinkulu zokuskena kusetshenziswa i-photoluminescence (PL) spectroscopy (1g). Isignali ye-photoluminescent yezendlalelo ngazinye ngaphakathi kwe-heterostructure icindezelwe kakhulu uma iqhathaniswa nesignali ye-monolayer ehlukanisiwe. Lokhu kuchazwa inqubo yokudlulisa inkokhiso ye-interlayer ngenxa yokusebenzisana kwe-interlayer, okuba kuqine nakakhulu ngemva kokudonsa.
Isithombe #2
Ukuze kulinganiswe ukugeleza kokushisa okuhambisanayo nezindiza ze-athomu ze-heterostructure, uchungechunge lwezendlalelo lwakhiwe ngendlela yamadivaysi kagesi angama-probe amane. Isendlalelo esiphezulu sama-electrode e-graphene contacts palladium (Pd) futhi sisetshenziswa njengehitha yokulinganisa i-Raman thermometry.
Le ndlela yokushisa kagesi inikeza ukulinganisa okunembile kwamandla okufaka. Enye indlela yokushisa engaba khona, i-optical, ingaba nzima kakhulu ukuyisebenzisa ngenxa yokungazi lutho kwama-coefficients wokumuncwa wezendlalelo ngazinye.
In I-2 ikhombisa isifunda sokulinganisa esine-probe, futhi 2b kukhombisa ukubuka okuphezulu kwesakhiwo esivivinywayo. Isheduli 2s ibonisa izici zokudlulisa ukushisa ezilinganisiwe zamadivayisi amathathu, eyodwa equkethe kuphela i-graphene futhi amabili aqukethe i-Gr/WSe22 kanye ne-Gr/MoSe2/WSe22 layer layers. Zonke izinhlobo zibonisa ukuziphatha okungaqondakali kwe-graphene, okuhlotshaniswa nokungabikho kwegebe lebhendi.
Kuphinde kwatholakala ukuthi ukuqhutshwa nokushisa kwamanje kwenzeka kungqimba olungaphezulu (i-graphene), njengoba ukuqhutshwa kwayo kukagesi kuyimiyalo eminingana yobukhulu obuphezulu kunaleyo ye-MoS2 ne-WSe22.
Ukuze kuboniswe ukufana kwamadivayisi ahloliwe, izilinganiso zathathwa kusetshenziswa i-Kelvin probe microscopy (KPM) kanye ne-scanning thermal microscopy (SThM). Eshadini 2d Izilinganiso ze-KPM ziboniswa kuveza umugqa wokusatshalaliswa okungaba khona. Imiphumela yokuhlaziywa kwe-SThM ikhonjisiwe ku 2s. Lapha sibona imephu yeziteshi ezishisiswe ngogesi ze-Gr/MoS2/WSe22, kanye nokuba khona kokufana ekushisiseni kwendawo.
Amasu okuskena achazwe ngenhla, ikakhulukazi i-SThM, aqinisekise ukufana kwesakhiwo esingaphansi kocwaningo, okungukuthi, ukufana kwayo, ngokuya ngamazinga okushisa. Isinyathelo esilandelayo kwakuwukubala izinga lokushisa lesendlalelo ngasinye kusetshenziswa i-Raman spectroscopy (okungukuthi, i-Raman spectroscopy).
Womathathu amadivayisi ahloliwe, ngalinye linendawo engu-~40 µm2. Kulesi simo, amandla we-heater ashintshwe ngo-9 mW, futhi amandla e-laser amuncwa ayengaphansi kuka-~5 μW nendawo ye-laser engu-~0.5 μm2.
Isithombe #3
Eshadini I-3 ukwanda kwezinga lokushisa (∆T) kwesendlalelo ngasinye kanye ne-substrate kubonakala njengoba amandla heater ku-Gr/MoS2/WSe22 heterostructure enyuka.
Imithambeka yomsebenzi womugqa wento ngayinye (ungqimba) ikhombisa ukumelana nokushisa (Rth=∆T/P) phakathi kwesendlalelo ngasinye kanye nosinki wokushisa. Uma kubhekwa ukusatshalaliswa okufanayo kokushisa endaweni, ukumelana nokushisa kungahlaziywa kalula ukusuka phansi kuye phezulu, lapho amanani abo enziwa ngendlela evamile ngendawo yesiteshi (WL).
U-L kanye no-W ubude nobubanzi besiteshi, obukhulu kakhulu kunobukhulu be-SiO2 substrate kanye nobude bokushisisa bokushisa obusemaceleni, obungu-~0.1 μm.
Ngakho-ke, singathola ifomula yokumelana nokushisa kwe-Si substrate, ezobukeka kanje:
Rth,Si ≈ (WL)1/2 / (2kSi)
Kulesi simo kSi ≈ 90 W m−1 K−1, okuyi-thermal conductivity elindelekile ye-substrate ene-doped kakhulu.
Umehluko phakathi kwe-Rth, i-WSe2 ne-Rth, i-Si iyisamba sokumelana nokushisa kwe-SiO2 engu-100 nm obukhulu kanye nokumelana nomngcele oshisayo (TBR) wesixhumi esibonakalayo se-WSe2/SiO2.
Uma sihlanganisa zonke izici ezingenhla, singathola ukuthi i-Rth,MoS2 − Rth,WSe2 = TBRMoS2/WSe2, kanye ne-Rth,Gr − Rth,MoS2 = TBRGr/MoS2. Ngakho-ke, kusukela kugrafu I-3 kuyenzeka kukhishwe inani le-TBR endaweni ngayinye ye-WSe2/SiO2, MoS2/WSe2 kanye ne-Gr/MoS2.
Okulandelayo, ososayensi baqhathanisa ukumelana nokushisa okuphelele kwazo zonke izakhiwo ze-heterostructures, zikalwa kusetshenziswa i-Raman spectroscopy kanye ne-thermal microscopy (3b).
I-Bilayer kanye ne-trilayer heterostructures ku-SiO2 ibonise ukumelana nokushisa okuphumelelayo ku-220 kuya ku-280 m2 K/GW ekamelweni lokushisa, okulingana nokumelana nokushisa kwe-SiO2 enogqinsi olungu-290 kuya ku-360 nm. Ngaphandle kweqiniso lokuthi ubukhulu be-heterostructures ngaphansi kocwaningo abukho ngaphezu kwe-2 nm (1d-1f), i-thermal conductivity yabo ingu-0.007-0.009 W m−1 K−1 ekamelweni lokushisa.
Isithombe #4
Isithombe sesi-4 sibonisa izilinganiso zazo zonke izakhiwo ezine kanye ne-thermal boundary conductivity (TBC) ye-interfaces yazo, esivumela ukuthi sihlole izinga lethonya lesendlalelo ngasinye kukumelana nokushisa okukalwe ngaphambilini (TBC = 1 / TBR).
Abacwaningi baqaphela ukuthi lesi isilinganiso sokuqala ngqa se-TBC sokuxhumana okuseduze kwe-athomu phakathi kwama-monolayers ahlukene (2D/2D), ikakhulukazi phakathi kwe-WSe2 kanye ne-SiO2 monolayers.
I-TBC yesixhumi esibonakalayo se-monolayer WSe2/SiO2 iphansi kunaleyo yesixhumi esibonakalayo se-WSe2/SiO2 ye-multilayer, okungamangazi njengoba i-monolayer inamamodi ephonon agobayo ambalwa kakhulu atholakalayo ukuze adluliselwe. Kalula nje, i-TBC yesixhumi esibonakalayo phakathi kwezingqimba ze-2D iphansi kune-TBC yesixhumi esibonakalayo phakathi kwesendlalelo se-2D ne-3D SiO2 substrate (4b).
Ukuze uthole ulwazi oluningiliziwe ngama-nuances ocwaningo, ngincoma ukubheka и kuyena.
Epilogue
Lolu cwaningo, njengoba ososayensi ngokwabo besho, lusinika ulwazi olungase lusetshenziswe ekusetshenzisweni kokuhlangana okushisayo kwe-athomu. Lo msebenzi wabonisa ukuthi kungenzeka ukudala ama-metamatadium afaka ukushisa lapho izakhiwo zawo zingatholakali emvelweni. Ngaphezu kwalokho, ucwaningo luphinde lwaqinisekisa ukuthi kungenzeka kwenziwe izilinganiso zokushisa ezinembile zezakhiwo ezinjalo, naphezu kwesikali se-athomu sezendlalelo.
I-heterostructures echazwe ngenhla ingaba yisisekelo "sezihlangu" ezishisayo ezikhanyayo futhi ezihlangene, ezikwazi, isibonelo, ukususa ukushisa ezindaweni ezishisayo kuma-electronics. Ngaphezu kwalokho, lobu buchwepheshe bungasetshenziswa kuma-generator we-thermoelectric noma kumadivayisi alawulwa ngokushisa, okwandisa ukusebenza kwawo.
Lolu cwaningo luphinde luqinisekise ukuthi isayensi yesimanje inesithakazelo esijulile esimisweni “sokusebenza kahle emthonjeni,” ongenakubizwa ngokuthi umbono oyisiphukuphuku, uma kubhekwa izinsiza ezilinganiselwe zeplanethi kanye nokukhula okuqhubekayo kwesidingo sazo zonke izinhlobo zokuqanjwa kabusha kwezobuchwepheshe.
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Source: www.habr.com