High-performance optoelectronic devices based on van der Waals vertical MoS₂/MoSe₂ heterostructures

Monolayer MoS₂ is a direct band gap semiconductor with large exciton binding energy, which is a promising candidate for the application of ultrathin optoelectronic devices. However, the optoelectronic performance of monolayer MoS₂ is seriously limited to its growth quality and carrier mobility. In this work, we report the direct vapor growth and the optoelectronic device of vertically-stacked MoS₂/MoSe₂ heterostructure, and further discuss the mechanism of improved device performance. The optical and high-resolution atomic characterizations demonstrate that the heterostructure interface is of high-quality without atomic alloying. Electrical transport measurements indicate that the heterostructure transistor exhibits a high mobility of 28.5 cm²/(V·s) and a high on/off ratio of 10⁷. The optoelectronic characterizations prove that the heterostructure device presents an enhanced photoresponsivity of 36 A/W and a remarkable detectivity of 4.8 × 10¹¹ Jones, which benefited from the interface induced built-in electric field and carrier dependent Coulomb screening effect. This work demonstrates that the construction of two-dimensional (2D) semiconductor heterostructures plays a significant role in modifying the optoelectronic device properties of 2D materials.