Gold-vapor-assisted chemical vapor deposition of aligned monolayer WSe₂ with large domain size and fast growth rate

Orientation-controlled growth of two-dimensional (2D) transition metal dichalcogenides (TMDCs) may enable many new electronic and optical applications. However, previous studies reporting aligned growth of WSe₂ usually yielded very small domain sizes. Herein, we introduced gold vapor into the chemical vapor deposition (CVD) process as a catalyst to assist the growth of WSe₂ and successfully achieved highly aligned monolayer WSe₂ triangular flakes grown on c-plane sapphire with large domain sizes (130 μm) and fast growth rate (4.3 μm·s^-1). When the aligned WSe₂ domains merged together, a continuous monolayer WSe₂ was formed with good uniformity. After transferring to Si/SiO₂ substrates, field effect transistors were fabricated on the continuous monolayer WSe₂, and an average mobility of 12 cm²·V^-1·s^-1 was achieved, demonstrating the good quality of the material. This report paves the way to study the effect of catalytic metal vapor in the CVD process of TMDCs and contributes a novel approach to realize the growth of aligned TMDC flakes.