Charge Separation at Mixed-Dimensional Single and Multilayer MoS2/Silicon Nanowire Heterojunctions

Alex Henning, Vinod K. Sangwan, Hadallia Bergeron, Itamar Balla, Zhiyuan Sun, Mark C Hersam, Lincoln J. Lauhon

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Layered two-dimensional (2-D) semiconductors can be combined with other low-dimensional semiconductors to form nonplanar mixed-dimensional van der Waals (vdW) heterojunctions whose charge transport behavior is influenced by the heterojunction geometry, providing a new degree of freedom to engineer device functions. Toward that end, we investigated the photoresponse of Si nanowire/MoS2 heterojunction diodes with scanning photocurrent microscopy and time-resolved photocurrent measurements. Comparison of n-Si/MoS2 isotype heterojunctions with p-Si/MoS2 heterojunction diodes under varying biases shows that the depletion region in the p-n heterojunction promotes exciton dissociation and carrier collection. We measure an instrument-limited response time of 1 μs, which is 10 times faster than the previously reported response times for planar Si/MoS2 devices, highlighting the advantages of the 1-D/2-D heterojunction. Finite element simulations of device models provide a detailed understanding of how the electrostatics affect charge transport in nanowire/vdW heterojunctions and inform the design of future vdW heterojunction photodetectors and transistors.

Original languageEnglish
Pages (from-to)16760-16767
Number of pages8
JournalACS Applied Materials and Interfaces
Volume10
Issue number19
DOIs
Publication statusPublished - May 16 2018

Keywords

  • mixed-dimensional heterojunction
  • MoS
  • nanowire
  • p-n heterojunction
  • photodetector
  • van der Waals

ASJC Scopus subject areas

  • Materials Science(all)

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