Polarity-tunable photocurrent through band alignment engineering in a high-speed WSe2/SnSediode with large negative responsivity

Sayantan Ghosh, Abin Varghese, Himani Jawa, Yuefeng Yin, Nikhil V. Medhekar, Saurabh Lodha

Research output: Contribution to journalArticleResearchpeer-review

38 Citations (Scopus)

Abstract

Excellent light-matter interaction and a wide range of thickness-tunable bandgaps in layered vdW materials coupled by the facile fabrication of heterostructures have enabled several avenues for optoelectronic applications. Realization of high photoresponsivity at fast switching speeds is a critical challenge for 2D optoelectronics to enable high-performance photodetection for optical communication. Moving away from conventional type-II heterostructure pn junctions towards a WSe2/SnSe2type-III configuration, we leverage the steep change in tunneling current along with a light-induced heterointerface band shift to achieve high negative photoresponsivity, while the fast carrier transport under tunneling results in high speed. In addition, the photocurrent can be controllably switched from positive to negative values, with ∼104× enhancement in responsivity, by engineering the band alignment from type-II to type-III using either the drain or the gate bias. This is further reinforced by electric-field dependent interlayer band structure calculations using density functional theory. The high negative responsivity of 2 × 104A/W and fast response time of ∼1 μs coupled with a polarity-tunable photocurrent can lead to the development of next-generation multifunctional optoelectronic devices.

Original languageEnglish
Pages (from-to)4578-4587
Number of pages10
JournalACS Nano
Volume16
Issue number3
DOIs
Publication statusPublished - 22 Mar 2022

Keywords

  • negative photocurrent
  • photodetection
  • tunnel conduction
  • type-III band alignment
  • vdW heterostructure

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