Heavy electron doping in monolayer MoS2 on a freestanding N-face GaN substrate

Abstract

This study explores how gallium nitride (GaN) surface polarity affects the optical properties and surface potential of MoS _2 . Using Raman spectroscopy, photoluminescence, and Kelvin force microscopy (KFM), significant electron doping (∼10 ^14 cm ^−2 ) was observed in MoS _2 on N-face GaN compared to Ga-face. photoluminescence spectra and the small contact potential difference of ∼30 mV measured by KFM provided evidence for polarity-dependent different doping levels. Additionally, KFM measurements also suggested a small band bending difference between Ga- and N-face GaN, likely due to interactions at the GaN/MoS _2 interface. This heavy doping contributes to the improved valley polarization of N-face GaN.

Keywords

• transition metal dichalcogenides
• gallium nitride
• photoluminescence
• doping
• valley polarization
• Kelvin force microscopy