Thin-film transition metal dichalcogenide alloys grown by patterned films of stacked Mo and W

Abstract

We report a chemical vapor deposition method where transition metal dichalcogenide growth is modified by changing the thickness and stacking sequence of patterned Mo and W composite films. The top metal thickness was kept constant at ∼ 200 nm while the bottom metal thickness was varied. For samples with W covered by Mo with W:Mo thickness ratios of approximately 1:20, 1:4 and 1:1, Mo_1-xW_xS₂ alloys were formed with concentrations of approximately 0–0.25, 0.25–0.50 and 0.75–1, respectively. With the stacking order reversed, there was no identifiable Mo present in the growth from the 1:20 and 1:4 Mo:W samples; however, for 1:1 Mo:W samples, about one third of the material had a concentration of ∼ 0.25 while the remaining two thirds had a concentration of 0.75–1.0.