Cov kws tshawb fawb los ntawm Moscow lub koom haum ntawm Physics thiab Technology tau tswj kom loj hlob atomically nyias zaj duab xis ntawm molybdenum disulfide ncua mus txog rau ob peb kaum centimeters square. Nws tau pom tias cov khoom siv cov qauv tuaj yeem hloov kho los ntawm qhov sib txawv ntawm qhov sib txawv ntawm qhov kub thiab txias. Cov yeeb yaj kiab, uas tseem ceeb rau kev siv hluav taws xob thiab optoelectronics, tau txais ntawm 900-1,000 ° C. Cov kev tshawb pom tau luam tawm hauv phau ntawv Journal ACS Applied Nano Materials.

Ob-seem cov ntaub ntawv tau txais kev txaus siab heev vim lawv cov khoom tshwj xeeb stemming los ntawm lawv cov qauv thiab quantum mechanical txwv. Tsev neeg ntawm 2-D cov ntaub ntawv suav nrog hlau, semimetals, semiconductors, thiab insulators. Graphene, uas yog tej zaum cov khoom 2-D nto moo tshaj plaws, yog ib qho monolayer ntawm carbon atoms. Nws muaj lub siab tshaj plaws tus nqi thauj mus los tau sau tseg rau hnub tim. Txawm li cas los xij, graphene tsis muaj qhov sib txawv hauv cov txheej txheem, thiab qhov ntawd txwv nws cov ntawv thov.

Tsis zoo li graphene, qhov zoo tshaj plaws dav ntawm bandgap hauv molybdenum disulfide (MoS2) ua rau nws haum rau siv hauv cov khoom siv hluav taws xob. Txhua txheej MoS2 muaj cov qauv sandwich, nrog ib txheej ntawm molybdenum nyem ntawm ob txheej ntawm sulfur atoms. Ob-dimensional van der Waals heterostructures, uas sib xyaw 2-D cov ntaub ntawv sib txawv, qhia cov lus cog tseg zoo ib yam. Qhov tseeb, lawv twb tau siv dav hauv kev siv hluav taws xob ntsig txog thiab catalysis. Wafer-scale (loj-thaj chaw) synthesis ntawm 2-D molybdenum disulfide qhia tau hais tias muaj peev xwm rau kev ua tiav ntawm kev tsim cov khoom siv hluav taws xob pob tshab thiab hloov tau yooj yim, kev sib txuas lus kho qhov muag rau cov khoos phis tawj tiam tom ntej, nrog rau lwm yam khoom siv hluav taws xob thiab optoelectronics.

"Txoj kev uas peb tau los ua ke los ua ke MoS2 suav nrog ob kauj ruam. Ua ntej, ib zaj duab xis ntawm MoO3 yog loj hlob siv atomic txheej deposition txheej txheem, uas muaj meej atomic txheej thickness thiab tso cai rau conformal txheej ntawm tag nrho cov nto. Thiab MoO3 tuaj yeem yooj yim tau ntawm wafers txog li 300 millimeters inch. Tom ntej no, cov zaj duab xis yog tshav kub-kho nyob rau hauv sulfur vapor. Yog li ntawd, cov pa oxygen atoms hauv MoO3 yog hloov los ntawm cov sulfur atoms, thiab MoS2 yog tsim. Peb twb tau kawm kom loj hlob atomically nyias MoS2 zaj duab xis ntawm thaj tsam txog li ob peb kaum square centimeters," piav qhia Andrey Markeev, tus thawj coj ntawm MIPT's Atomic Layer Deposition Lab.

Cov kws tshawb fawb tau txiav txim siab tias cov qauv ntawm zaj duab xis nyob ntawm qhov kub ntawm sulfurization. Cov yeeb yaj kiab sulfurized ntawm 500 ° C muaj crystalline nplej, ob peb nanometers txhua, kos rau hauv amorphous matrix. Ntawm 700 ° C, cov crystallites yog li 10-20 nm thoob plaws thiab S-Mo-S cov khaubncaws sab nraud povtseg yog oriented perpendicular rau saum npoo. Raws li qhov tshwm sim, qhov saum npoo muaj ntau dangling bonds. Cov qauv zoo li no qhia tau tias muaj kev ua haujlwm siab catalytic hauv ntau qhov kev tshwm sim, suav nrog cov tshuaj tiv thaiv hydrogen evolution. Rau MoS2 siv rau hauv cov khoom siv hluav taws xob, S-Mo-S cov khaubncaws sab nraud povtseg yuav tsum tau sib npaug rau saum npoo, uas ua tiav ntawm sulfurization kub ntawm 900-1,000 ° C. Cov yeeb yaj kiab uas tau tshwm sim yog nyias li 1.3 nm, lossis ob txheej molecular, thiab muaj qhov chaw lag luam tseem ceeb (piv txwv li, loj txaus).

MoS2 films synthesized nyob rau hauv kev pom zoo tau nkag mus rau hauv cov hlau-dielectric-semiconductor qauv qauv, uas yog ua raws li ferroelectric hafnium oxide thiab ua qauv ib qho kev cuam tshuam ntawm transistor. MoS2 zaj duab xis nyob rau hauv cov qauv no tau txais kev pab raws li ib tug semiconductor channel. Nws cov conductivity tau tswj los ntawm kev hloov lub polarization kev taw qhia ntawm ferroelectric txheej. Thaum nyob rau hauv kev sib cuag nrog MoS2, cov khoom La: (HfO2-ZrO2), uas tau tsim ua ntej hauv MIPT lab, tau pom tias muaj qhov seem polarization ntawm kwv yees li 18 microcoulombs ib square centimeter. Nrog rau kev hloov pauv ntawm 5 lab lub voj voog, nws tau tshaj tawm lub ntiaj teb cov ntaub ntawv dhau los ntawm 100,000 cycles rau silicon channel.