Ka whakamahia e mātou te mātai whakaahua-whakamārama wā-me-te-koki (tr-ARPES) hei tirotiro i te whakawhiti utu tere rawa i roto i te hanganga heteroepial epitaxial i hangaia mai i te paparanga kotahi WS2 me te graphene. Ka whakakotahihia e tēnei hanganga heteroe ngā painga o te semiconductor āputa-tika me te hononga porowhita-porowhita kaha me te taunekeneke mārama-matū kaha ki ērā o te haurua-metal e manaaki ana i ngā kaikawe papatipu kore me te nekenekehanga tino teitei me te roa o te oranga porowhita. I kitea e mātou, i muri i te whakahihiko whakaahua i te oro ki te A-exciton i roto i te WS2, ka tere te whakawhiti o ngā kōhao whakahihiko whakaahua ki roto i te paparanga graphene i te mea ka noho tonu ngā irahiko whakahihiko whakaahua ki roto i te paparanga WS2. Ko te āhua whakawhiti wehewehe-utu hua kua kitea he oranga o te ~1 ps. E kī ana mātou ko ā mātou kitenga he rerekētanga i roto i te wāhi wāhanga marara i puta mai i te whakaritenga whanaunga o ngā roopu WS2 me te graphene e whakaatuhia ana e ngā ARPES taumira-teitei. I te taha o te whakahihiko whatu whiriwhiri-porowhita, ko te hanganga heteroe WS2/graphene i tirotirohia ka whakarato pea i tētahi tūāpapa mō te werohanga porowhita whatu whai hua ki roto i te graphene.
Nā te wātea mai o ngā rauemi rerekē e rua-ahu kua huaki ake te huarahi ki te waihanga i ngā hanganga hetero-anga hou, angiangi rawa, me ngā mahi hou katoa i runga i te tirotiro dielectric kua whakaritea me ngā pānga tata (1–3). Kua kitea ngā taputapu taunakitanga-o-te-kaupapa mō ngā tono ā muri ake nei i roto i te mara o ngā hikohiko me ngā optoelectronics (4–6).
I konei, ka arotahi mātou ki ngā hanganga heterostructures epitaxial van der Waals kei roto ko te paparanga kotahi WS2, he semiconductor āputa-tika me te hononga porowhita-porowhita kaha me te wehenga porowhita nui o te hanganga roopu nā te pakaru o te ōritetanga hurihuri (7), me te paparanga kotahi graphene, he semi-metal me te hanganga roopu kōniko me te nekehanga kawe tino teitei (8), i whakatipuria ki runga i te SiC (0001) kua mutu te hauwai. Ko ngā tohu tuatahi mō te whakawhiti utu tino tere (9–15) me ngā pānga hononga porowhita-porowhita i puta mai i te tata (16–18) ka waiho ko te WS2/graphene me ngā heterostructures rite hei kaitono mō ngā tono optoelectronic (19) me te optospintronic (20) ā muri ake nei.
I whai mātou ki te whakaatu i ngā ara whakangā o ngā takirua irahiko-pōha i hangaia i roto i te WS2/graphene me te tirotiro tukunga whakaahua kua whakatauhia te wā me te koki (tr-ARPES). Mō tēnā kaupapa, ka whakaohohia e mātou te hanganga heterostructure me ngā pāta papu 2-eV e whakaata ana ki te A-exciton i roto i te WS2 (21, 12) ka tukuna ngā irahiko whakaahua me te pāta tuarua o te tirotiro kua whakaroahia te wā i te kaha photon 26-eV. Ka whakatauhia e mātou te kaha nekeneke me te koki tukunga o ngā irahiko whakaahua me te tātari hemispherical hei mahi a te whakaroa tirotiro papu kia uru atu ai ki ngā hihiri kawe nekehanga, kaha, me te wā kua whakatauhia. Ko te kaha me te whakatau wā he 240 meV me te 200 fs, ia.
Ka whakaratohia e ā mātou hua he taunakitanga tika mō te whakawhiti utu tere rawa i waenga i ngā paparanga epitaxially kua whakaritea, e whakaū ana i ngā tohu tuatahi i runga i ngā tikanga whatu-katoa i roto i ngā hanganga heterostructures rite tonu kua huihui ā-ringa me te whakaritenga azimuthal o ngā paparanga (9–15). Hei tāpiri, ka whakaatuhia e mātou he tino koretake tēnei whakawhiti utu. Ka whakaatuhia e ā mātou inenga he āhua whakawhiti kua wehea-utu kāore i kitea i mua me ngā irahiko me ngā kōhao kua whakahihikohia e te whakaahua kei roto i te paparanga WS2 me te graphene, ia, e ora ana mō te ~1 ps. Ka whakamāramahia e mātou ā mātou kitenga i runga i ngā rerekētanga o te wāhi marara mō te whakawhiti irahiko me te kōhao i puta mai i te whakaritenga whanaunga o ngā roopu WS2 me te graphene e whakaatuhia ana e ngā ARPES taumira teitei. I te whakakotahitanga me te whakaoho whatu hurihuri me te whiriwhiri-awaawa (22–25) ka whakaratohia pea e ngā hanganga heterostructures WS2/graphene he tūāpapa hou mō te werohanga hurihuri whatu tere rawa ki roto i te graphene.
E whakaatu ana te Pikitia 1A i tētahi inenga ARPES taumira-teitei i whiwhihia mā te whakamahi i tētahi rama helium o te hanganga roopu i te ahunga ΓK o te hanganga heterostructure epitaxial WS2/graphene. Kua kitea kua tāpirihia he kōhao ki te koeko Dirac me te pūwāhi Dirac kei te ∼0.3 eV i runga ake i te pūmanawa matū taurite. Kua kitea ko te tihi o te roopu valence WS2 wehe-hurihuri kei te ∼1.2 eV i raro iho i te pūmanawa matū taurite.
(A) Te au whakaahua taurite i inehia i te ahunga-ΓK me te rama helium kore-polarized. (B) Te au whakaahua mō te whakaroa kino o te papu-tirotiro i inehia me ngā pāoro ultraviolet tino polarized p i te kaha photon 26-eV. Ko ngā rārangi hina me te whero kua pōkaikaha e tohu ana i te tūranga o ngā kōtaha rārangi i whakamahia hei tango i ngā tūranga tihi whakawhiti i te Pikitia 2. (C) Ngā huringa i puta mai i te papu o te au whakaahua 200 fs i muri i te whakaoho whakaahua i te kaha photon papu o te 2 eV me te rere o te papu o te 2 mJ/cm2. Ko te pikinga me te ngaronga o ngā irahiko whakaahua e whakaatuhia ana i te whero me te kikorangi. Ko ngā pouaka e tohu ana i te rohe whakauru mō ngā tohu papu-tirotiro e whakaatuhia ana i te Pikitia 3.
E whakaatu ana te Pikitia 1B i tētahi whakaahua tr-ARPES o te hanganga roopu e tata ana ki ngā pūwāhi K WS2 me te graphene i inehia ki ngā pāoro ultraviolet tino 100-fs i te kaha photon 26-eV i te whakaroa kino o te papu-tirotiro i mua i te taenga mai o te pāoro papu. I konei, kāore te wehenga hurihuri e whakatauhia nā te whakahekenga tauira me te aroaro o te pāoro papu 2-eV e puta ai te whānui o te utu ātea o ngā āhuatanga hihi. E whakaatu ana te Pikitia 1C i ngā huringa i puta mai i te papu o te iahiko whakaahua e pā ana ki te Pikitia 1B i te whakaroa papu-tirotiro o te 200 fs i te wā e eke ai te tohu papu-tirotiro ki tōna taumata teitei. Ko ngā tae whero me te kikorangi e tohu ana i te pikinga me te ngaronga o ngā irahiko whakaahua, ia.
Hei tātari i tēnei hihiri whai kiko, tuatahi ka whakatauhia e mātou ngā tūranga tihi tauwhiro o te roopu valence WS2 me te roopu π-graphene i ngā rārangi pōturi i te Pikitia 1B e whakamāramahia ana i roto i ngā Rauemi Tāpiri. Ka kitea e mātou ka neke ake te roopu valence WS2 mā te 90 meV (Pikitia 2A) ā, ka neke iho te roopu π-graphene mā te 50 meV (Pikitia 2B). Ko te roanga o te ora taupū o ēnei nekehanga he 1.2 ± 0.1 ps mō te roopu valence o WS2 me te 1.7 ± 0.3 ps mō te roopu π-graphene. Ka whakaratohia e ēnei nekehanga tihi he taunakitanga tuatahi mō te utu tauwhiro o ngā paparanga e rua, i reira ka whakanuia (ka whakaitihia) e te utu pai (kino) tāpiri te kaha here o ngā āhua hiko. Kia mahara ko te nekehanga ake o te roopu valence WS2 te take o te tohu papu-tirotiro e kitea ana i te rohe kua tohua e te pouaka pango i te Pikitia 1C.
Te huringa o te tūranga tihi o te roopu valence WS2 (A) me te roopu π-graphene (B) hei pānga o te whakaroa papu-tirotiro me ngā taunga taupū (ngā rārangi matotoru). Ko te roanga o te nekehanga WS2 i roto i (A) he 1.2 ± 0.1 ps. Ko te roanga o te nekehanga graphene i roto i (B) he 1.7 ± 0.3 ps.
Muri iho, ka whakauruhia e mātou te tohu papu-tirotiro ki runga i ngā wāhi kua tohua e ngā pouaka tae i te Pikitia 1C, ā, ka tuhia ngā tatau hua hei pānga o te whakaroa papu-tirotiro i te Pikitia 3. E whakaatu ana te kōpiko 1 i te Pikitia 3 i ngā hihiri o ngā kaikawe whakaahua-whakaoho tata ki te raro o te roopu arataki o te paparanga WS2 me te roanga ora o te 1.1 ± 0.1 ps i whiwhi mai i te taunga taupū ki ngā raraunga (tirohia ngā Rauemi Tāpiri).
Ko ngā tohu o te papu-tirotiro hei mahi a te whakaroa i whiwhi mā te whakauru i te iahiko whakaahua ki runga i te rohe e tohuhia ana e ngā pouaka i te Pikitia 1C. Ko ngā rārangi matotoru he taunga taupū ki ngā raraunga. Piko (1) Taupori kawe whakawhiti i roto i te roopu kawe o WS2. Piko (2) Tohu papu-tirotiro o te roopu π o te graphene i runga ake i te pūmanawa matū taurite. Piko (3) Tohu papu-tirotiro o te roopu π o te graphene i raro iho i te pūmanawa matū taurite. Piko (4) Tohu papu-tirotiro kupenga i roto i te roopu valence o WS2. Ko ngā roanga ora e kitea ana ko te 1.2 ± 0.1 ps i roto i te (1), 180 ± 20 fs (hua) me te ~2 ps (ngaronga) i roto i te (2), me te 1.8 ± 0.2 ps i roto i te (3).
I ngā kōpiko 2 me te 3 o te Pikitia 3, ka whakaaturia te tohu papu-tirotiro o te roopu-graphene π. Ka kitea e mātou he poto ake te roa o te ora o te whiwhinga o ngā irahiko i runga ake i te pūmanawa matū taurite (kōpiko 2 i te Pikitia 3) (180 ± 20 fs) ki te whakataurite ki te ngaronga o ngā irahiko i raro iho i te pūmanawa matū taurite (1.8 ± 0.2 ps i te kōpiko 3 Pikitia 3). I tua atu, ka kitea ko te whiwhinga tuatahi o te iahiko whakaahua i te kōpiko 2 o te Pikitia 3 ka huri hei ngaronga i te t = 400 fs me te roa o te ora o te ~2 ps. Ka kitea te kore taurite i waenga i te whiwhinga me te ngaronga i roto i te tohu papu-tirotiro o te graphene paparanga kotahi kāore i kitea (tirohia te pikitia S5 i roto i ngā Rauemi Tāpiri), e tohu ana ko te kore taurite he hua o te hononga paparanga i roto i te hanganga heterostructure WS2/graphene. Ko te kitenga o te pikinga poto me te ngaronga roa i runga ake me raro iho i te pūmanawa matū taurite, e tohu ana ka tangohia pai ngā irahiko mai i te paparanga graphene i te wā e whakakorikoria ana te hanganga heterostructure. Nō reira, ka noho te paparanga graphene hei utu pai, he rite ki te pikinga o te kaha here o te roopu π i kitea i te Pikitia 2B. Ko te nekehanga iho o te roopu π ka tango i te hiku kaha-teitei o te tohatoha Fermi-Dirac taurite mai i runga ake i te pūmanawa matū taurite, e whakamārama ana i te huringa o te tohu o te tohu papu-tirotiro i te pihi 2 o te Pikitia 3. Ka whakaaturia e mātou i raro nei ka whakarei ake i tēnei pānga e te ngaronga rangitahi o ngā irahiko i roto i te roopu π.
E tautokona ana tēnei āhuatanga e te tohu pūma-tirotiro kupenga o te roopu valence WS2 i te pihi 4 o te Pikitia 3. I whiwhihia ēnei raraunga mā te whakauru i ngā tatau i runga i te horahanga i homai e te pouaka pango i te Pikitia 1B e hopu ana i ngā irahiko i tukuna mai i te roopu valence i ngā whakaroa katoa o te pūma-tirotiro. I roto i ngā pae hapa whakamātautau, kāore mātou e kite i tētahi tohu mō te aroaro o ngā kōhao i roto i te roopu valence o WS2 mō tētahi whakaroa o te pūma-tirotiro. E tohu ana tēnei, i muri i te whakahihiko whakaahua, ka tere te whakakī anō i ēnei kōhao i te wā poto ki tā mātou whakataunga wā.
Hei whakarato i te taunakitanga whakamutunga mō tā mātou whakapae mō te wehenga utu tere rawa i roto i te hanganga heterostructure WS2/graphene, ka whakatauhia e mātou te maha o ngā kōhao i whakawhitia ki te paparanga graphene e ai ki te whakaahuatanga taipitopito i roto i ngā Rauemi Tāpiri. I roto i te poto, ko te tohatoha hiko tauwhiro o te roopu π i whakauruhia ki te tohatoha Fermi-Dirac. Kātahi ka tatauhia te maha o ngā kōhao mai i ngā uara hua mō te pūmanawa matū tauwhiro me te pāmahana hiko. Ka whakaaturia te hua i te Pikitia 4. I kitea e mātou he tapeke o te ∼5 × 1012 kōhao/cm2 i whakawhitia mai i WS2 ki te graphene me te roanga ora taupū o te 1.5 ± 0.2 ps.
Te huringa o te maha o ngā kōhao i te roopu-π hei pānga o te whakaroa o te papu-tirotiro me te taunga taupū, ka puta he roanga ora o te 1.5 ± 0.2 ps.
Mai i ngā kitenga i roto i ngā Pikitia 2 ki te 4, ka puta te pikitia moroiti e whai ake nei mō te whakawhiti utu tino tere i roto i te hanganga heterostructure WS2/graphene (Pikitia 5). Ko te photoexcitation o te hanganga heterostructure WS2/graphene i te 2 eV te nuinga e whakakī ana i te A-exciton i roto i te WS2 (Pikitia 5A). Ka taea te whakakī i ngā whakaoho hiko tāpiri puta noa i te pūwāhi Dirac i roto i te graphene me waenganui i ngā roopu WS2 me te graphene engari he iti ake te whai huatanga. Ko ngā kōhao photoexcited i roto i te roopu valence o WS2 ka whakakīhia anō e ngā irahiko e ahu mai ana i te roopu π-graphene i runga i te tauine wā poto ki te whakataurite ki tā mātou taumira wā (Pikitia 5A). Ko te roanga ora o ngā irahiko photoexcited i roto i te roopu kawe hiko o WS2 he ∼1 ps (Pikitia 5B). Heoi, e ∼2 ps te roa hei whakakī anō i ngā kōhao i roto i te roopu π-graphene (Pikitia 5B). E tohu ana tēnei, i tua atu i te whakawhiti irahiko tika i waenga i te roopu arataki WS2 me te roopu π-graphene, me whai whakaaro ki ētahi atu ara whakangā—tērā pea mā roto i ngā āhua hapa (26)—kia mārama ai ki te whanaketanga katoa.
(A) Mā te whakaoho whakaahua i te wā e pā ana ki te WS2 A-exciton i te 2 eV ka werohia ngā irahiko ki roto i te roopu kawe o WS2. Ka whakakīia tonutia ngā kōhao e rite ana i roto i te roopu valence o WS2 e ngā irahiko mai i te roopu graphene π. (B) Ko te roanga ora o ngā kaikawe whakaoho whakaahua i roto i te roopu kawe o WS2 he ∼1 ps. Ka ora ngā kōhao i roto i te roopu graphene π mō te ∼2 ps, e tohu ana i te hiranga o ngā hongere marara tāpiri e tohuhia ana e ngā pere kua tapahia. Ko ngā rārangi pango kua tapahia i roto i (A) me (B) e tohu ana i ngā nekehanga roopu me ngā huringa o te pūmanawa matū. (C) I roto i te āhua whakawhiti, he utu kino te paparanga WS2 i te mea he utu pai te paparanga graphene. Mō te whakaoho whiriwhiri-hurihuri me te mārama porowhita-polarized, e tumanakohia ana ka whakaatu ngā irahiko whakaoho whakaahua i roto i te WS2 me ngā kōhao e rite ana i roto i te graphene i te polarization hurihuri rerekē.
I te āhua whakawhiti, kei roto i te awhi kawe o WS2 ngā irahiko kua whakahihikohia e te whakaahua, ko ngā kōhao kua whakahihikohia e te whakaahua kei roto i te awhi-π o te graphene (Pikitia 5C). Ko te tikanga he utu kino te paparanga WS2, ā, he utu pai te paparanga graphene. Koinei te take o ngā nekehanga tihi whakawhiti (Pikitia 2), te kore taurite o te tohu papu-tirotiro graphene (ngā pihi 2 me te 3 o te Pikitia 3), te korenga o ngā kōhao i te awhi valence o WS2 (pihi 4 Pikitia 3), me ngā kōhao tāpiri i te awhi-π graphene (Pikitia 4). Ko te roanga o te ora o tēnei āhua wehe-utu he ~1 ps (pihi 1 Pikitia 3).
Kua kitea ngā āhua tauwhitiwhiti wehe-utu rite tonu i roto i ngā hanganga rerekē van der Waals e pā ana i hangaia mai i ngā semiconductors āputa-tika e rua me te whakaritenga roopu momo II me te āputa roopu taurite (27–32). I muri i te photoexcitation, i kitea ko ngā irahiko me ngā kōhao ka tere te neke ki raro o te roopu kawe me te tihi o te roopu valence, ia, kei roto i ngā paparanga rerekē o te hanganga rerekē (27–32).
Mō tā mātou hanganga heterostructure WS2/graphene, ko te wāhi tino pai mō ngā irahiko me ngā kōhao kei te taumata Fermi i roto i te paparanga graphene whakarewa. Nō reira, e tika ana kia tere te whakawhiti o ngā irahiko me ngā kōhao ki te roopu π-graphene. Heoi, e whakaatu mārama ana ā mātou inenga he nui ake te whai huatanga o te whakawhiti kōhao (<200 fs) i te whakawhiti irahiko (∼1 ps). E kī ana mātou ko te whakaritenga pūngao whanaunga o te WS2 me ngā roopu graphene tēnei e whakaatuhia ana i te Pikitia 1A e tuku ana i te maha atu o ngā āhua whakamutunga e wātea ana mō te whakawhiti kōhao ki te whakawhiti irahiko e ai ki te whakaaro tata nei (14, 15). I tēnei wā, ki te whakaaro he ∼2 eV te āputa roopu WS2, ko te pūwāhi Dirac graphene me te pūmanawa matū taurite kei te ∼0.5 me te ∼0.2 eV i runga ake i waenganui o te āputa roopu WS2, ia, e pakaru ana i te ōritetanga irahiko-kōhao. E kitea ana e mātou ko te maha o ngā āhua whakamutunga e wātea ana mō te whakawhiti pū kōhao he ~6 ngā wā te nui ake i te whakawhiti irahiko (tirohia ngā Rauemi Tāpiri), koia te take e matapaetia ai ka tere ake te whakawhiti pū kōhao i te whakawhiti irahiko.
Heoi anō, me whai whakaaro anō hoki tētahi pikitia mōkitokito katoa o te whakawhiti utu kore-taurite tino tere kua kitea ki te taupatupatu i waenga i ngā porowhita e hanga ana i te mahi ngaru A-exciton i roto i te WS2 me te graphene π-band, ia, ngā hongere marara irahiko-irahiko me te irahiko-phonon rerekē tae atu ki ngā here i whakatakotoria e te nekehanga, te pūngao, te hurihuri, me te tiaki pseudospin, te awe o ngā wiri plasma (33), me te tūranga o te whakaoho nekehanga pea o ngā wiri phonon taurite e taea ai te takawaenga i te whakawhiti utu (34, 35). Waihoki, ka taea te whakapae mēnā ko te āhua whakawhiti utu kua kitea he whakaoho whakawhiti utu, he takirua irahiko-pōhao kore utu rānei (tirohia ngā Rauemi Tāpiri). Me whai atu i ngā rangahau ariā e neke atu ana i te whānuitanga o tēnei pepa hei whakamārama i ēnei take.
Hei whakarāpopototanga, kua whakamahia e mātou te tr-ARPES hei ako i te whakawhiti utu ā-paparanga tino tere i roto i te hanganga heterostructure epitaxial WS2/graphene. I kitea e mātou, i te wā e whakaohohia ana i te wā e pāngia ana ki te A-exciton o WS2 i te 2 eV, ka tere te whakawhiti o ngā kōhao kua whakaohohia ki roto i te paparanga graphene, i te wā e noho tonu ana ngā irahiko kua whakaohohia ki roto i te paparanga WS2. I kīia tēnei nā te mea he nui ake te maha o ngā āhua whakamutunga e wātea ana mō te whakawhiti kōhao i te whakawhiti irahiko. I kitea ko te roanga o te ora o te āhua whakawhiti kua wehea-utu he ~1 ps. I te taha o te whakaoho whatu whiriwhiri-hurihuri mā te whakamahi i te mārama porowhita-polarized (22–25), ka haere tahi pea te whakawhiti utu tino tere i kitea me te whakawhiti hurihuri. I tēnei take, ka whakamahia pea te hanganga heterostructure WS2/graphene i tirotirohia mō te werohanga hurihanga whatu whai hua ki roto i te graphene ka hua ake he taputapu optospintronic hou.
I whakatipuria ngā tauira graphene ki runga i ngā anga whakapūmau 6H-SiC(0001) arumoni mai i SiCrystal GmbH. I runga i te tuaka ngā anga kua tāpirihia ki te N me te tapahi hē i raro i te 0.5°. I tāia te papa SiC ki te hauwai hei tango i ngā karawarawa me te whiwhi i ngā papa papatahi noa. Kātahi ka tāia te mata Si-terminated ma, papatahi hoki mā te whakamahana i te tauira i roto i te āhuarangi Ar i te 1300°C mō te 8 meneti (36). Pēnei, i whiwhi mātou i tētahi paparanga waro kotahi i reira ka hangaia e ia ngota waro tuatoru he hononga honohono ki te papa SiC (37). Kātahi ka hurihia tēnei paparanga hei graphene kua tāpirihia ki te kōhao tū-kore kua whakakotahihia ki te sp2 mā te whakauru hauwai (38). Ka kiia ēnei tauira ko te graphene/H-SiC(0001). I mahia te tukanga katoa i roto i tētahi rūma tipu Black Magic arumoni mai i Aixtron. I whakahaerehia te tipu WS2 i roto i tētahi tauhohenga pakitara wera paerewa mā te whakatakoto i te kohu matū pēhanga-iti (39, 40) mā te whakamahi i ngā paura WO3 me S me te ōwehenga papatipu o te 1:100 hei matū mua. I puritia ngā paura WO3 me S ki te 900 me te 200°C, ia. I whakatakotoria te paura WO3 tata ki te papa. I whakamahia te argon hei hau kawe me te rere o te 8 sccm. I puritia te pēhanga i roto i te tauhohenga ki te 0.5 mbar. I tautuhia ngā tauira mā te karuārai irahiko tuarua, te karuārai kaha ngota, te Raman, me te karuārai photoluminescence, me te diffraction irahiko pūngao-iti. I whakaatuhia e ēnei inenga e rua ngā rohe WS2 kotahi-kiriata kei reira te ahunga ΓK-, te ahunga ΓK'-ranei e hangai ana ki te ahunga ΓK- o te paparanga graphene. I rerekē ngā roa taha rohe i waenga i te 300 me te 700 nm, ā, ko te tapeke o te kapinga WS2 i tata ki te ~40%, he mea e tika ana mō te tātaritanga ARPES.
I whakahaerehia ngā whakamātautau ARPES pūmau me te whakamahi i tētahi tātari porowhita-rua (SPECS PHOIBOS 150) mā te whakamahi i tētahi pūnaha taputapu-kitenga hono-utu mō te kimi i te kaha irahiko me te nekehanga e rua-ahu. I whakamahia te irahiko He Iα kotahi-tae kore-polarized (21.2 eV) o tētahi pūtake tukunga He rere-teitei (VG Scienta VUV5000) mō ngā whakamātautau tukunga whakaahua katoa. Ko te kaha me te taumira koki i roto i ā mātou whakamātautau he pai ake i te 30 meV me te 0.3° (e rite ana ki te 0.01 Å−1), ia. I whakahaerehia ngā whakamātautau katoa i te pāmahana rūma. He tikanga tino tairongo te ARPES ki te mata. Hei pana i ngā irahiko whakaahua mai i te WS2 me te paparanga graphene, i whakamahia ngā tauira me te kapinga WS2 kāore i oti o te ~40%.
I ahu mai te whakatakotoranga tr-ARPES i te whakakaha Titanium:Sapphire 1-kHz (Coherent Legend Elite Duo). I whakamahia te 2 mJ o te mana putanga mō te whakaputa i ngā harmonika teitei i roto i te argon. Ko te mārama ultraviolet tino nui i puta mai i roto i te monochromator kumete e whakaputa ana i ngā pāorooro tirotiro 100-fs i te kaha photon 26-eV. I tukuna te 8mJ o te mana putanga whakakaha ki roto i te whakakahaorooro whatu (HE-TOPAS mai i te Whakawhitinga Marama). I whakanekehia te auau o te hihi tohu i te kaha photon 1-eV i roto i te karaihe beta barium borate hei whiwhi i ngā pāorooro papu 2-eV. I mahia ngā inenga tr-ARPES me te tātari hemispherical (SPECS PHOIBOS 100). Ko te kaha whānui me te taumira wā he 240 meV me te 200 fs, ia.
Kei te wātea ngā rauemi tāpiri mō tēnei tuhinga i http://advances.sciencemag.org/cgi/content/full/6/20/eaay0761/DC1
He tuhinga urunga-tuwhera tēnei e tohatohahia ana i raro i ngā tikanga o te raihana Creative Commons Attribution-NonCommercial, e whakaae ana ki te whakamahinga, te tohatoha, me te tārua i roto i tētahi momo pāpāho, mena ehara te whakamahinga i puta mai i te mea mō ngā painga arumoni, ā, mena kua whakahuatia tika te mahi taketake.
TUHI: Ka tonoa noa e mātou tō wāhitau īmēra kia mōhio ai te tangata e taunaki ana koe i te whārangi ki a ia e hiahia ana koe kia kite rātou i taua whārangi, ehara hoki i te mēra para. Kāore mātou e hopu i tētahi wāhitau īmēra.
Hei whakamātautau tēnei pātai mēnā he manuhiri tangata koe, hei ārai hoki i ngā tuku pāme aunoa.
Na Sven Aeschlimann, Antonio Rossi, Mariana Chávez-Cervantes, Razvan Krause, Benito Arnoldi, Benjamin Stadtmüller, Martin Aeschlimann, Stiven Forti, Filippo Fabbri, Camilla Coletti, Isabella Gierz
Ka whakakitea e mātou te wehenga utu tino tere i roto i te hanganga heterostructure WS2/graphene, ka taea ai te werohanga hurihuri whatu ki roto i te graphene.
Na Sven Aeschlimann, Antonio Rossi, Mariana Chávez-Cervantes, Razvan Krause, Benito Arnoldi, Benjamin Stadtmüller, Martin Aeschlimann, Stiven Forti, Filippo Fabbri, Camilla Coletti, Isabella Gierz
Ka whakakitea e mātou te wehenga utu tino tere i roto i te hanganga heterostructure WS2/graphene, ka taea ai te werohanga hurihuri whatu ki roto i te graphene.
© 2020 American Association for the Advancement of Science. Katoa nga mana. Ko AAAS te hoa o HINARI, AGORA, OARE, CHORUS, CLOCKSS, CrossRef me COUNTER.Science Advances ISSN 2375-2548.
Wā tuku: Mei-25-2020