Photogating WS2 Photodetectors Using Embedded WSe2 Charge Puddles

Tsung Han Tsai, Zheng Yong Liang, Yung Chang Lin, Cheng Chieh Wang, Kuang I. Lin, Kazu Suenaga, Po Wen Chiu

研究成果: Article同行評審

6 引文 斯高帕斯(Scopus)


Performance of 2D photodetectors is often predominated by charge traps that offer an effective photogating effect. The device features an ultrahigh gain and responsivity, but at the cost of a retarded temporal response due to the nature of long-lived trap states. In this work, we devise a gain mechanism that originates from massive charge puddles formed in the type-II 2D lateral heterostructures. This concept is demonstrated using graphene-contacted WS2 photodetectors embedded with WSe2 nanodots. Upon light illumination, photoexcited carriers are separated by the built-in field at the WSe2/WS2 heterojunctions (HJs), with holes trapped in the WSe2 nanodots. The resulting WSe2 hole puddles provide a photoconductive gain, as electrons are recirculating during the lifetime of holes that remain trapped in the puddles. The WSe2/WS2 HJ photodetectors exhibit a responsivity of 3 × 102 A/W with a gain of 7 × 102 electrons per photon. Meanwhile, the zero-gate response time is reduced by 5 orders of magnitude as compared to the prior reports for the graphene-contacted pristine WS2 monolayer and WS2/MoS2 heterobilayer photodetectors due to the ultrafast intralayer excitonic dynamics in the WSe2/WS2 HJs.

頁(從 - 到)4559-4566
期刊ACS nano
出版狀態Published - 2020 四月 28

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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