Defect-Controlled Nucleation and Orientation of WSe 2 on hBN: A Route to Single-Crystal Epitaxial Monolayers

Xiaotian Zhang, Fu Zhang, Yuanxi Wang, Daniel S. Schulman, Tianyi Zhang, Anushka Bansal, Nasim Alem, Saptarshi Das, Vincent Henry Crespi, Mauricio Terrones Maldonado, Joan Marie Redwing

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

A defect-controlled approach for the nucleation and epitaxial growth of WSe 2 on hBN is demonstrated. The WSe 2 domains exhibit a preferred orientation of over 95%, leading to a reduced density of inversion domain boundaries (IDBs) upon coalescence. First-principles calculations and experimental studies as a function of growth conditions and substrate pretreatment confirm that WSe 2 nucleation density and orientation are controlled by the hBN surface defect density rather than thermodynamic factors. Detailed transmission electron microscopy analysis provides support for the role of single-atom vacancies on the hBN surface that trap W atoms and break surface symmetry leading to a reduced formation energy for one orientation of WSe 2 domains. Through careful control of nucleation and extended lateral growth time, fully coalesced WSe 2 monolayer films on hBN were achieved. Low-temperature photoluminescence (PL) measurements and transport measurements of back-gated field-effect transistor devices fabricated on WSe 2 /hBN films show improved optical and electrical properties compared to films grown on sapphire under similar conditions. Our results reveal an important nucleation mechanism for the epitaxial growth of van der Waals heterostructures and demonstrate hBN as a superior substrate for single-crystal transition-metal dichalcogenide (TMD) films, resulting in a reduced density of IDBs and improved properties. The results motivate further efforts focused on the development of single crystal hBN substrates and epilayers for synthesis of wafer-scale single crystal TMD films.

Original languageEnglish (US)
Pages (from-to)3341-3352
Number of pages12
JournalACS nano
Volume13
Issue number3
DOIs
StatePublished - Mar 26 2019

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Monolayers
Nucleation
routes
Single crystals
nucleation
Defects
single crystals
defects
metal films
Epitaxial growth
transition metals
Transition metals
inversions
Substrates
energy of formation
surface defects
Atoms
pretreatment
coalescing
Aluminum Oxide

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

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title = "Defect-Controlled Nucleation and Orientation of WSe 2 on hBN: A Route to Single-Crystal Epitaxial Monolayers",
abstract = "A defect-controlled approach for the nucleation and epitaxial growth of WSe 2 on hBN is demonstrated. The WSe 2 domains exhibit a preferred orientation of over 95{\%}, leading to a reduced density of inversion domain boundaries (IDBs) upon coalescence. First-principles calculations and experimental studies as a function of growth conditions and substrate pretreatment confirm that WSe 2 nucleation density and orientation are controlled by the hBN surface defect density rather than thermodynamic factors. Detailed transmission electron microscopy analysis provides support for the role of single-atom vacancies on the hBN surface that trap W atoms and break surface symmetry leading to a reduced formation energy for one orientation of WSe 2 domains. Through careful control of nucleation and extended lateral growth time, fully coalesced WSe 2 monolayer films on hBN were achieved. Low-temperature photoluminescence (PL) measurements and transport measurements of back-gated field-effect transistor devices fabricated on WSe 2 /hBN films show improved optical and electrical properties compared to films grown on sapphire under similar conditions. Our results reveal an important nucleation mechanism for the epitaxial growth of van der Waals heterostructures and demonstrate hBN as a superior substrate for single-crystal transition-metal dichalcogenide (TMD) films, resulting in a reduced density of IDBs and improved properties. The results motivate further efforts focused on the development of single crystal hBN substrates and epilayers for synthesis of wafer-scale single crystal TMD films.",
author = "Xiaotian Zhang and Fu Zhang and Yuanxi Wang and Schulman, {Daniel S.} and Tianyi Zhang and Anushka Bansal and Nasim Alem and Saptarshi Das and Crespi, {Vincent Henry} and {Terrones Maldonado}, Mauricio and Redwing, {Joan Marie}",
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language = "English (US)",
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Defect-Controlled Nucleation and Orientation of WSe 2 on hBN : A Route to Single-Crystal Epitaxial Monolayers. / Zhang, Xiaotian; Zhang, Fu; Wang, Yuanxi; Schulman, Daniel S.; Zhang, Tianyi; Bansal, Anushka; Alem, Nasim; Das, Saptarshi; Crespi, Vincent Henry; Terrones Maldonado, Mauricio; Redwing, Joan Marie.

In: ACS nano, Vol. 13, No. 3, 26.03.2019, p. 3341-3352.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Defect-Controlled Nucleation and Orientation of WSe 2 on hBN

T2 - A Route to Single-Crystal Epitaxial Monolayers

AU - Zhang, Xiaotian

AU - Zhang, Fu

AU - Wang, Yuanxi

AU - Schulman, Daniel S.

AU - Zhang, Tianyi

AU - Bansal, Anushka

AU - Alem, Nasim

AU - Das, Saptarshi

AU - Crespi, Vincent Henry

AU - Terrones Maldonado, Mauricio

AU - Redwing, Joan Marie

PY - 2019/3/26

Y1 - 2019/3/26

N2 - A defect-controlled approach for the nucleation and epitaxial growth of WSe 2 on hBN is demonstrated. The WSe 2 domains exhibit a preferred orientation of over 95%, leading to a reduced density of inversion domain boundaries (IDBs) upon coalescence. First-principles calculations and experimental studies as a function of growth conditions and substrate pretreatment confirm that WSe 2 nucleation density and orientation are controlled by the hBN surface defect density rather than thermodynamic factors. Detailed transmission electron microscopy analysis provides support for the role of single-atom vacancies on the hBN surface that trap W atoms and break surface symmetry leading to a reduced formation energy for one orientation of WSe 2 domains. Through careful control of nucleation and extended lateral growth time, fully coalesced WSe 2 monolayer films on hBN were achieved. Low-temperature photoluminescence (PL) measurements and transport measurements of back-gated field-effect transistor devices fabricated on WSe 2 /hBN films show improved optical and electrical properties compared to films grown on sapphire under similar conditions. Our results reveal an important nucleation mechanism for the epitaxial growth of van der Waals heterostructures and demonstrate hBN as a superior substrate for single-crystal transition-metal dichalcogenide (TMD) films, resulting in a reduced density of IDBs and improved properties. The results motivate further efforts focused on the development of single crystal hBN substrates and epilayers for synthesis of wafer-scale single crystal TMD films.

AB - A defect-controlled approach for the nucleation and epitaxial growth of WSe 2 on hBN is demonstrated. The WSe 2 domains exhibit a preferred orientation of over 95%, leading to a reduced density of inversion domain boundaries (IDBs) upon coalescence. First-principles calculations and experimental studies as a function of growth conditions and substrate pretreatment confirm that WSe 2 nucleation density and orientation are controlled by the hBN surface defect density rather than thermodynamic factors. Detailed transmission electron microscopy analysis provides support for the role of single-atom vacancies on the hBN surface that trap W atoms and break surface symmetry leading to a reduced formation energy for one orientation of WSe 2 domains. Through careful control of nucleation and extended lateral growth time, fully coalesced WSe 2 monolayer films on hBN were achieved. Low-temperature photoluminescence (PL) measurements and transport measurements of back-gated field-effect transistor devices fabricated on WSe 2 /hBN films show improved optical and electrical properties compared to films grown on sapphire under similar conditions. Our results reveal an important nucleation mechanism for the epitaxial growth of van der Waals heterostructures and demonstrate hBN as a superior substrate for single-crystal transition-metal dichalcogenide (TMD) films, resulting in a reduced density of IDBs and improved properties. The results motivate further efforts focused on the development of single crystal hBN substrates and epilayers for synthesis of wafer-scale single crystal TMD films.

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SN - 1936-0851

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