Electrical Properties and Thermal Annealing Effects of Polycrystalline MoS₂-MoS_X Nanowalls Grown by Sputtering Deposition Method

Abstract

Straightforward growth of nanostructured low-bandgap materials is a key issue in mass production for electronic device applications. We report here facile nanowall growth of MoS2-MoSX using sputter deposition and investigate the electronic properties of the nanowalls. MoS2-MoSX nanowalls become gradually thicker and taller, with primarily (100)-plane growth directions, with increasing deposition time. Nanowalls combine with nearby walls when a rapid thermal annealing (RTA, 200 °C–500 °C) process is applied. All samples have conventional low-bandgap semiconductor behavior with exponential resistance increase as measurement temperature decreases. The 750 nm-thick MoS2-MoSX nanowalls have a sheet carrier mobility of up to 2 cm2·V−1·s−1 and bulk carrier concentration of ~1017–1019 cm−3 range depending on RTA temperature. Furthermore, perpendicular field-dependent magnetoresistance at 300 K shows negative magnetoresistance behavior, which displays resistance decay by applying a magnetic field (MR ratio in the −1 % range at 5 T). Interestingly, 400 °C RTA treated samples show a resistance upturn when applying an external magnetic field of more than 3 T. Our research suggests tuneability of MoS2 nanowall size and mesoscopic electronic transport properties.

Keywords

• MoS₂
• nanowall
• crystal growth
• sputter deposition
• MoS₂ polycrystal characterization