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Charge Density Depinning in Defective MoTe 2 Transistor by Oxygen Intercalation
Author(s) -
Liu Xiaochi,
Qu Deshun,
Wang Lu,
Huang Ming,
Yuan Yahua,
Chen Peng,
Qu Yuanyuan,
Sun Jian,
Yoo Won Jong
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202004880
Subject(s) - materials science , density functional theory , ohmic contact , condensed matter physics , charge density , annealing (glass) , molybdenum , transistor , tellurium , optoelectronics , nanotechnology , computational chemistry , voltage , electrical engineering , chemistry , physics , metallurgy , engineering , layer (electronics) , quantum mechanics
Molybdenum ditelluride is prone to various defects. Among them, tellurium vacancies lead to the significant reduction of band gap as revealed by density functional theory (DFT) calculations. They are responsible for inducing spatial band structure variation and localized charge puddles in MoTe 2 . As a result, undesirable charge density pinning is anticipated in the channel‐dominated MoTe 2 field‐effect transistors (FETs) even with much improved ohmic contacts, resulting in poor device characteristics, for example, conductivity minimum point (CMP) pinning and weak gate tunability. DFT simulations suggest occupying tellurium vacancies with oxygen can effectively restore MoTe 2 to its intrinsic properties and therefore remove charge density pinning. Experimentally, this can be realized by oxygen intercalation during low‐pressure annealing without bringing in additional defects to MoTe 2 . The CMP is unpinned in the FETs made of annealed MoTe 2 , which can be tuned by changing the contact metals with varied work functions. Moreover, much improved device characteristics, for example, a high hole current density exceeding 20 μAμm −1 , a record high hole mobility of 77 cm 2 V −1 s −1 , are obtained.