Scalable van der Waals Heterojunctions for High-Performance Photodetectors

Chao Hui Yeh, Zheng Yong Liang, Yung Chang Lin, Tien Lin Wu, Ta Fan, Yu Cheng Chu, Chun Hao Ma, Yu Chen Liu, Ying-hao Chu, Kazutomo Suenaga, Po Wen Chiu*

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Atomically thin two-dimensional (2D) materials have attracted increasing attention for optoelectronic applications in view of their compact, ultrathin, flexible, and superior photosensing characteristics. Yet, scalable growth of 2D heterostructures and the fabrication of integrable optoelectronic devices remain unaddressed. Here, we show a scalable formation of 2D stacks and the fabrication of phototransistor arrays, with each photosensing element made of a graphene-WS 2 vertical heterojunction and individually addressable by a local top gate. The constituent layers in the heterojunction are grown using chemical vapor deposition in combination with sulfurization, providing a clean junction interface and processing scalability. The aluminum top gate possesses a self-limiting oxide around the gate structure, allowing for a self-aligned deposition of drain/source contacts to reduce the access (ungated) channel regions and to boost the device performance. The generated photocurrent, inherently restricted by the limited optical absorption cross section of 2D materials, can be enhanced by 2 orders of magnitude by top gating. The resulting photoresponsivity can reach 4.0 A/W under an illumination power density of 0.5 mW/cm 2 , and the dark current can be minimized to few picoamperes, yielding a low noise-equivalent power of 2.5 × 10 -16 W/Hz 1/2 . Tailoring 2D heterostacks as well as the device architecture moves the applications of 2D-based optoelectronic devices one big step forward.

Original languageEnglish
Pages (from-to)36181-36188
Number of pages8
JournalACS Applied Materials and Interfaces
Volume9
Issue number41
DOIs
StatePublished - 18 Oct 2017

Keywords

  • graphene
  • heterostructure
  • photoresponsivity
  • two-dimensional materials
  • WS

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    Yeh, C. H., Liang, Z. Y., Lin, Y. C., Wu, T. L., Fan, T., Chu, Y. C., Ma, C. H., Liu, Y. C., Chu, Y., Suenaga, K., & Chiu, P. W. (2017). Scalable van der Waals Heterojunctions for High-Performance Photodetectors. ACS Applied Materials and Interfaces, 9(41), 36181-36188. https://doi.org/10.1021/acsami.7b10892