High-Performance WSe2 Phototransistors with 2D/2D Ohmic Contacts

Tianjiao Wang, Kraig Andrews, Arthur Bowman, Tu Hong, Michael Koehler, Jiaqiang Yan, David Mandrus, Zhixian Zhou, Ya Qiong Xu

Research output: Contribution to journalArticlepeer-review

115 Scopus citations

Abstract

We report high-performance WSe2 phototransistors with two-dimensional (2D) contacts formed between degenerately p-doped WSe2 and undoped WSe2 channel. A photoresponsivity of ∼600 mA/W with a high external quantum efficiency up to 100% and a fast response time (both rise and decay times) shorter than 8 μs have been achieved concurrently. More importantly, our WSe2 phototransistor exhibits a high specific detectivity (∼1013 Jones) in vacuum, comparable or higher than commercial Si- and InGaAs-based photodetectors. Further studies have shown that the high photoresponsivity and short response time of our WSe2 phototransistor are mainly attributed to the lack of Schottky-barriers between degenerately p-doped WSe2 source/drain contacts and undoped WSe2 channel, which can reduce the RC time constant and carrier transit time of a photodetector. Our experimental results provide an accessible strategy to achieve high-performance WSe2 phototransistor architectures by improving their electrical transport and photocurrent generation simultaneously, opening up new avenues for engineering future 2D optoelectronic devices.

Original languageEnglish
Pages (from-to)2766-2771
Number of pages6
JournalNano Letters
Volume18
Issue number5
DOIs
StatePublished - May 9 2018

Keywords

  • Photocurrent
  • TMDs
  • WSe
  • ohmic contacts
  • photodetector

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