Tunable van der Waals Doping in WS₂/CrOCl Heterostructure by Interlayer Coupling Engineering

In contrast with substitutional doping, van der Waals doping is essential in two-dimensional (2D) semiconductors to avoid carrier scattering. Here, we take the WS₂/CrOCl heterostructure (HS) as an example to investigate tunable van der Waals doping by uniaxial strain engineering. Because of different work functions, electrons transfer to CrOCl from WS₂, leading to electrostatic doping of WS₂ and a built-in electric field from WS₂ to CrOCl. Photoexcited electrons also transfer from WS₂ to CrOCl but are hindered by the built-in electric field, saturating the doping in WS₂. Moreover, uniaxial strain can continuously modulate the interlayer coupling of WS₂/CrOCl HS, leading not only to electrostatic doping but also to photoinduced doping in WS₂. These results demonstrate that uniaxial strain is an effective strategy to tailor van der Waals doping in 2D semiconductors for applications in 2D electronics and optoelectronics.