Low-damaged p-type doping of MoS₂ using direct nitrogen plasma modulated by toroidal-magnetic-field

Low damaged doping of two-dimensional (2D) materials proves to be a significant obstacle in realizing fundamental devices such as p-n junction diodes and transistors due to its atom layer thickness. In this work, the defect formation energy and p-type conduction behavior of nitrogen plasma doping are investigated by first principle calculation. Low damaged substitutional p-type doping in MoS₂ using low energy nitrogen plasma composed of N⁺ and N₂ ⁺ is achieved by a novel toroidal magnetic field (TMF). The TMF helps to raise the concentration of N₂ ⁺ ions at low RF power condition. The electrical characteristics of double-layer MoS₂ field-effect transistors (FETs) clearly show an efficient p-type doping behavior. Atomic force microscope is applied to verify the slight damage in MoS₂. X-ray photoelectron spectroscopy, photoluminescence and Raman spectroscopy confirm the effective p-type doping characteristic with weak damage. These findings provide a low damage technology for efficient carrier modulation of MoS₂ and other homogeneous TMDC materials, which overcomes barriers in developing 2D electronic and optoelectronic devices.