Unveiling the potential of vanadium-doped CVD-grown p-type MoS2 in vertical homojunction UV–Vis photodiodes

Abstract

2D materials are a popular choice for the fabrication of p-n diodes for applications in integrated optoelectronics owing to their outstanding properties such as strong light-matter interactions, high mobility, and tunable band gap. The synthesis of monolayer and few-layer 2D materials with both p-type and n-type behavior is thus essential for the design and fabrication of such devices. However, the large-scale direct synthesis of p-type 2D materials is still a challenge as most of these materials are either n-type or ambipolar. Here, we report the successful synthesis of large-area, p-type MoS2 layers doped with vanadium on SiO2/Si substrates, achieving flake sizes >100 μm. By varying the concentration of the vanadium precursor, we precisely controlled the doping level, achieving vanadium atomic percentages ranging from 0.70 % to 1.57 %. Back gate field-effect transistors (FETs) were fabricated, enabling the tuning of device characteristics to exhibit ambipolar or p-type behavior. Moreover, a vertical p-n MoS2 homojunction was fabricated for rectification and optoelectronic applications, demonstrating a high responsivity of up to 978.1 A/W and a specific detectivity (D*) of 1.06 × 1012 Jones at λ = 365 nm with varied powers of the incident light source. This work demonstrates the role of vanadium as a dopant for tunable electrical transport behavior as well as for the fabrication of a photodiode, which can be used for high-performance optoelectronic devices in the future.