Enhanced near infrared and gate tunable photoresponse of MoSe₂ transistor enabled by 2D hetero contact engineering

The excellent physical features of two-dimensional (2D) layered materials make them very promising for electronic and optoelectronic applications. Here, we investigated the gate-tunable and broadband (220, 365, 460, 510, 840 and 1020 nm) photoresponse of MoSe₂ transistor with metallic (Cr–Au/MoSe₂) and van der Waals (vdWs) hetero MoSe₂/WTe₂ contacts. Our study intends to investigate the underlying mechanism of photogeneration and carrier's transport process by Cr–Au/MoSe₂ and hetero MoSe₂/WTe₂ contacts in the MoSe₂ transistor. Since, our research revealed that MoSe₂ devices with hetero MoSe₂/WTe₂ contacts exhibited remarkable performance, including high responsivity (R) of about 11.23 × 10⁵ mA/W, exceptional external quantum efficiency (EQE) of 6.3 × 10⁵ %, and detectivity (D*⁾ of 4.61 × 10¹⁰ Jones compared to metallic contacts. This implies that the enhanced performance of our devices with 2D hetero-contacts could be attributed to reduced contact resistance, interlayer charge transfer and interlayer excitons in MoSe₂/WTe₂ heterostructure. Also, the gate-controlled response and broadband capabilities of van der Waals 2D heterostructures hold significant promises for a wide range of optoelectronic applications, including photodetectors, optical sensors, and visual imaging systems.