Comparative study of WSe2 thin films synthesized via pre-deposited WO3 and W precursor material selenization

Abstract

Layered two-dimensional (2D) materials, such as p-type WSe2, are potential key materials in the manufacture of the next generation electronic devices. One of the remaining main challenges is the large area growth of high-quality films. A potential large-scale 2D WSe2 synthesis method is conversion (selenization) of a pre-deposited sacrificial precursor coating. However, its use is still limited, mainly due to a lack of understanding the growth mechanisms involved. Here, we have studied and compared properties of thin crystalline WSe2 films prepared via selenization of sputter-deposited sacrificial WO3 and W films. Surface morphology of the as-grown films was studied using a scanning electron microscope complemented with an atomic force microscope. The structure and chemical composition were confirmed by X-ray diffraction and micro-Raman spectroscopy, respectively. On-chip photoconductive devices were made using the standard photolithography process, and their photoresponse was investigated with 405 nm wavelength light. For the electrical characterization, field effect transistors (FETs) were made to measure output and transfer curves. The results obtained give insight into the growth of crystalline WSe2 via sacrificial film selenization.