High-Performance Self-Powered Photodetectors Based on TMD Alloy/GaAs van der Waals Heterojunctions for Infrared Light Communication

In recent years, the demand for high-speed infrared light communication has increased the performance requirement for infrared photodetectors (PDs). Two-dimensional layered material (2DLM)/GaAs heterojunctions PDs can be self-powered with simple structure and no dangling bonds. However, 2DLM faces the problems of limited structure quantity and significant influence from deep level defects, which limits the band modulation and the performance of PDs. In this work, transition metal dichalcogenide (TMD) alloy/GaAs van der Waals heterojunctions PDs have been constructed, achieving band alignment of type II band structure. The as-fabricated MoS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.62</sub> Se<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.38</sub>/GaAs PDs present a high responsivity (1.54 A/W) and fast response speed with the rise/fall time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$90~\mu $ </tex-math></inline-formula>s/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$275~\mu $ </tex-math></inline-formula>s at 0 bias voltage. Furthermore, a demonstration of infrared light communication is presented based on MoS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.62</sub> Se<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.38</sub>/GaAs PDs. This study sheds light that the TMD alloy/GaAs heterojunctions have great potential in the infrared PDs and light communication.