Investigating interface effects on the single MoS₂ flake placed on SiO₂ and BN surfaces

Due to the atomic thickness, electrical properties of two-dimensional (2D) materials such as MoS₂ are very sensitive to the interface and the underneath substrate. In previous reports, it was discovered that the MoS₂ placed on or sheathed with BN exhibited prominent electrical behaviors. However, the exact comparison of electrical properties of atomic thin MoS₂ placed on either BN or SiO₂ has not been explored yet. Here we placed the BN flake on the Si wafer capped with 300-nm thick SiO₂ and attached a few-layer MoS₂ flake with one part on BN and the other part on SiO₂ surfaces. The as-attached MoS₂ on both BN and SiO₂ was processed to make field-effect transistors and properties of electron transport and device performances were measured. Through a systematic study, it is found that the MoS₂/BN reveals a much lower Schottky barrier and specific contact resistivity as compared with MoS2/SiO₂. For all samples, the MoS₂/BN always shows a higher mobility while the temperature behavior presents either ascending or descending mobilities with increasing temperature. The MoS₂/BN presents a low interface trap density as well. In summary, the using of BN certainly prohibits some interface disorders coming from SiO₂ while there are other intrinsic disorders in MoS₂ that could severely degrade electrical properties of the 2D MoS₂.