Multi-wafer-scale growth of WSe2 films using a traveling flow-type reactor with a remote thermal Se cracker

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have demonstrated superior electrical and optical characteristics and are expected to replace silicon in semiconductor materials. However, in practice the use of TMDCs remains a challenge due to the lack of a suitable method for the large-scale synthesis of TMDCs. Herein we demonstrated a multi-wafer-scale growth method to obtain very uniform and continuous 2D WSe2 films by combining the selenization of the W metal using thermally cracked Se molecules, a metal-agglomeration-suppressed growth technique, and a traveling flow-type reactor. The usefulness of the traveling flow reactor must be attributed to the self-saturated selenization of a very thin W metal precursor film on a large-area substrate. The number of 2D WSe2 layers was easily controlled by varying the thickness of the W precursor. Raman scattering and thickness measurements showed that WSe2 films grew uniformly on three 4-inch Si wafers at once, at both 530 and 600 °C. The average Hall mobility and carrier concentration of 6-nm-thick p-type WSe2 films on the three wafers were 22.8 cm2 V−1 s−1 and 3.69 × 1016 cm−3, respectively. The field effect (FE) transistor with the 6-nm WSe2 channel and SiO2 back gate insulator also showed p-type transfer characteristics. The formation of a WSe2/MoSe2 vertical heterostructure also demonstrated the usefulness of the method proposed herein.