Realization of Diodes via MoS₂/WSe₂/Ni BJT-Like Structures

The p-n diodes are crucial in electronics and optoelectronics. One approach to forming a p-n diode involves using a MoS2/WSe2 heterojunction. However, to achieve ohmic contact with the metal, MoS2 and WSe2 typically require different electrode materials. We present a strategy to fabricate MoS2/WSe2 heterojunction devices using a single metal nickel (Ni) as electrodes, with performance tuned solely by varying contact positions. When the electrodes contact both materials on either side, the device suppresses current flow in both directions. However, when one electrode contacts MoS2 and the other contacts the heterojunction stack, the device yields pronounced rectification behavior, achieving a rectification ratio (RR) of 565, tunable via gate voltage. This enhancement arises as WSe2 effectively acts as a base region, akin to that in bipolar junction transistors (BJTs), facilitating electron collection with minimal recombination. The device exhibits superlinear optical power dependence at zero bias, and has a fast response with a rise 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">$67~\mu $ </tex-math></inline-formula> s and a 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">$60~\mu $ </tex-math></inline-formula> s. Our approach offers valuable guidance for designing next-generation electronics.