Phonon Lifetimes in Boron-Isotope-Enriched Graphene- Hexagonal Boron Nitride Devices

Alexandra Brasington, Song Liu, Takashi Taniguchi, Kenji Watanabe, James H. Edgar, Brian J. LeRoy, Arvinder Sandhu

Research output: Contribution to journalArticlepeer-review

Abstract

Using hexagonal boron nitride (hBN) as a substrate for graphene has shown faster carrier cooling which makes it ideal for high-power graphene-based devices. However, the effect of using boron-isotope-enriched hBN has not been explored. Herein, femtosecond pump-probe spectroscopy is utilized to measure and compare the time dynamics of photo-excited carriers in graphene-hBN heterostructures for hBN with the natural distribution of boron isotopes (20% 10B and 80% 11B) and hBN enriched to 100% 10B and 11B. The carriers cool down faster for systems with isotopically pure hBN substrates by a factor of ≈1.7 times. This difference in relaxation times arises from the interfacial coupling between carriers in graphene and the hBN phonon modes. The results show that the boron isotopic purity of the hBN substrate can help to reduce the hot phonon bottleneck that limits the cooling in graphene devices.

Original languageEnglish (US)
JournalPhysica Status Solidi - Rapid Research Letters
DOIs
StateAccepted/In press - 2022

Keywords

  • 2D heterostructures
  • carrier cooling
  • conductance
  • graphene
  • hBN
  • phonons

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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