Quaternery two dimensional transiton metal dichalcogenide alloys*

Monolayers of 2D TMDs, due to their unique band gap are useful in various optoelectronic devices. Alloying in 2D TMDs has gained importance due to its band gap tunability. However this tunability could futher be improved by increasing number of components, which provides more flexibility and degress of freedom. In the present work, quaternary alloys (Mo_xW_1-xS_2ySe_2(1-y)) (0< x,y <1) have been synthesised using CVD. The composition of the alloy has been tuned by changing the growth temperature, resulting in wide band gap tunability from 1.6 to 1.85 eV. Detailed DFT calcaulations support the experimental data. This wide range of band gap tunability would open the doors for 2D TMDs to be used in applications like laser diodes and LEDs.