Chain Vacancies in 2D Crystals

Jiong Zhao, Honggi Nam, Thuc Hue Ly, Seok Joon Yun, Sera Kim, Suyeon Cho, Heejun Yang, Young Hee Lee

Research output: Journal article publicationJournal articleAcademic researchpeer-review

13 Citations (Scopus)

Abstract

KGaA, Weinheim Defects in bulk crystals can be classified into vacancies, interstitials, grain boundaries, stacking faults, dislocations, and so forth. In particular, the vacancy in semiconductors is a primary defect that governs electrical transport. Concentration of vacancies depends mainly on the growth conditions. Individual vacancies instead of aggregated vacancies are usually energetically more favorable at room temperature because of the entropy contribution. This phenomenon is not guaranteed in van der Waals 2D materials due to the reduced dimensionality (reduced entropy). Here, it is reported that the 1D connected/aggregated vacancies are energetically stable at room temperature. Transmission electron microscopy observations demonstrate the preferential alignment direction of the vacancy chains varies in different 2D crystals: MoS2and WS2prefer (Formula presented.) direction, while MoTe2prefers (Formula presented.) direction. This difference is mainly caused by the different strain effect near the chalcogen vacancies. Black phosphorous also exhibits directional double-chain vacancies along 〈01〉 direction. Density functional theory calculations predict that the chain vacancies act as extended gap (conductive) states. The observation of the chain vacancies in 2D crystals directly explains the origin of n-type behavior in MoTe2devices in recent experiments and offers new opportunities for electronic structure engineering with various 2D materials.
Original languageEnglish
Article number1601930
JournalSmall
Volume13
Issue number1
DOIs
Publication statusPublished - 4 Jan 2017
Externally publishedYes

Keywords

  • ab initio
  • black phosphorous
  • transition metal dichalcogenide
  • transmission electron microscopy
  • vacancy defects

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Engineering (miscellaneous)

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