Synthesis of monolayer vanadium‐doped MoSe 2 for n‐to‐p type conversion and rectifying p–n homojunction devices

Doping for two‐dimensional (2D) transition metal dichalcogenides (TMDCs) is a promising strategy for developing next‐generation electronic and optoelectronic devices. However, achieving control over the concentration and uniformity of dopant in monolayer 2D TMDCs remains challenging. Here, we report the synthesis of monolayer vanadium (V)‐doped MoSe 2 with tunable doping concentrations using liquid precursor‐based chemical vapor deposition (CVD). By adjusting the concentration of liquid precursors, we successfully control the V‐doping level of the MoSe 2 . As the V‐doping level is increased, red‐shifted peaks are observed in both Raman and photoluminescence (PL) spectra. X‐ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) analyses confirm that V atoms substituted Mo sites within the MoSe 2 lattice. We fabricated field‐effect transistors (FETs) based on pristine MoSe 2 and V‐doped MoSe 2 to investigate their electronic properties. The electronic characterizations show that the n‐type characteristics of pristine MoSe 2 are turned to p‐type upon vanadium doping, indicating that the substituted V atoms act as p‐type dopants. The V‐doped MoSe 2 FET exhibits a carrier mobility of 2.11 cm 2 V −1 s −1 , showing a significant improvement compared to pristine MoSe 2 (8.5 × 10 −2 cm 2 V −1 s −1 ). Furthermore, the fabricated pristine MoSe 2 /V‐doped MoSe 2 homojunction devices exhibit rectification behavior.