Electron Beam-Induced defects in Mo2N thin films for surface-enhanced Raman Scattering

The development of cost-effective and high-performance surface enhanced Raman Scattering (SERS) substrate materials has been desired in recent years. Electron beam irradiation is a universal adaptable and efficient technology that can alter the optical and electrical properties of materials by introducing molecular and electronic defects. In this work, planar molybdenum nitride (Mo 2 N) substrates for SERS were synthesized by room-temperature magnetron sputtering. Electron beam irradiation was used to introduce nitrogen-vacancy defects in Mo 2 N thin films to modify the surface topographic properties, energy band structure, and density of states of Mo 2 N films, which improved light-material interaction, light-trapping ability, and charge-transfer efficiency, and resulted in significantly enhanced SERS performance of Mo 2 N films. The Mo 2 N-20 kGy films showed Raman enhancement factor of 1.18 × 10 7 and a detection limit as low as 10 − 9 M. Through the combination of the photoinduced charge transfer (PICT) mechanism and localized surface plasmon resonance effects (LSPR), the irradiated Mo 2 N films had more significant SERS characteristics than that of pristine Mo 2 N films with only the PICT mechanism. This study provides an effective theoretical and practical foundation for the development of sensitive SERS substrates free of precious metals.