4.8 Article

Epitaxial Topological Insulator Bi2Te3 for Fast Visible to Mid-Infrared Heterojunction Photodetector by Graphene As Charge Collection Medium

Journal

ACS NANO
Volume 16, Issue 3, Pages 4851-4860

Publisher

AMER CHEMICAL SOC
DOI: 10.1021/acsnano.2c00435

Keywords

topological insulator; Bi2Te3; broadband photodetection; fast photodetector; mid-infrared

Funding

  1. National Natural Science Foundation of China [61922022, 62175026, 61875031]

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The researchers have successfully achieved large area and high-quality epitaxial growth of topological insulator Bi2Te3 directly on GaAs wafers, and fabricated a Gr/Bi2Te3/GaAs heterojunction array photodetector using graphene, which exhibited broadband photodetection capabilities from visible to mid-infrared and a fast response speed.
Three dimensional topological insulators have a thriving application prospect in broadband photodetectors due to the possessed topological quantum states. Herein, a large area and uniform topological insulator bismuth telluride (Bi2Te3) layer with high crystalline quality is directly epitaxial grown on GaAs(111)B wafer using a molecular beam epitaxy process, ensuring efficient out-of-plane carriers transportation due to reduced interface defects influence. By tiling monolayer graphene (Gr) on the as-prepared Bi2Te3 layer, a Gr/Bi2Te3/GaAs heterojunction array prototype was further fabricated, and our photodetector array exhibited the capability of sensing ultrabroad photodetection wavebands from visible (405 nm) to mid-infrared (4.5 mu m) with a high specific detectivity (D*) up to 10(12) Jones and a fast response speed at about microseconds at room temperature. The enhanced device performance can be attributed to enhanced light-matter interaction at the high-quality heterointerface of Bi2Te3/GaAs and improved carrier collection efficiency through graphene as a charge collection medium, indicating an application prospect of topological insulator Bi2Te3 for fast-speed broadband photodetection up to a mid-infrared waveband. This work demonstrated the potential of integrated topological quantum materials with a conventional functional substrate to fabricate the next generation of broadband photodetection devices for uncooled focal plane array or infrared communication systems in future.

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