Phase engineering and optical properties of 2D MoSe 2: Promise and pitfalls

Eve D. Hanson, Laura M. Lilley, Jeffrey D. Cain, Shiqiang Hao, Edgar Palacios, Koray Aydin, Chris Wolverton, Thomas Meade, Vinayak P. Dravid*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Phase engineering monolayer MoS 2 , selectively controlling the MoS 2 2H to 1T′ transition via lithium intercalation, has driven recent excitement in the nanoscale electronics field, due to resultant MoS 2 contact resistance reduction and the compatibility of MoS 2 with CMOS device architecture. Here, we report the “on-chip” 2H to 1T′ transition for the related MoSe 2 system, which has a smaller 1.55 eV 2H bandgap, and for which the 1T′ phase transformation should be more energetically favorable. We report the first on-chip 2H to 1T′ transformation of monolayer MoSe 2 on both SiO 2 and sapphire substrates. The on-chip 1T′–MoSe 2 shows higher transparency despite an increased number of metallic states, indicating tunable optoelectronic properties with potential applications in transparent electrodes and energy harvesting. We also describe the challenges introduced by on-chip phase engineering via n-butyllithium exposure. Density functional theory (DFT) calculations indicate that Li + ions are required on both sides of the MoSe 2 monolayer to create a strong thermodynamic driving force for the 1T′ transformation. We observe that patterned n-butyllithium exposures can be inconsistent, with widely variable kinetics. Due to manifest n-butyllithium-engineered 1T′ MoSe 2 stability concerns we propose the process is an unreliable processing technique for 2D electronics.

Original languageEnglish (US)
Pages (from-to)219-226
Number of pages8
JournalMaterials Chemistry and Physics
Volume225
DOIs
StatePublished - Mar 1 2019

Funding

This material is partially based upon work supported by the National Science Foundation under Grant no. DMR-1507810 . This work made use of the EPIC, SPID and Keck-II facility of the NUANCE Center at Northwestern University , which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource ( NSF NNCI-1542205 ); the MRSEC program ( NSF DMR-1720139 ) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. J.D.C. is supported by the Department of Defense through the National Defense Science and Engineering Fellowship (NDSEG) Program. J.D.C. also gratefully acknowledges support from the Ryan Fellowship and the Northwestern University International Institute for Nanotechnology . This material is based upon work supported by the Materials Research Science and Engineering Center ( NSF-MRSEC ) ( DMR-1720139 ) of Northwestern University. K.A. also acknowledges partial support from the AFOSR under Award No. FA9550-12-1-0280 and the Institute for Sustainability and Energy at Northwestern (ISEN) through ISEN Booster Award. S.H. and C.W. (DFT calculations) acknowledge support by the U.S. Department of Energy, Office of Science, Basic Energy Sciences , under Grant No. DEFG02-07ER46433 .

Keywords

  • 2D materials
  • MoSe
  • Nanomaterials
  • Phase engineering

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics

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