Emergence of Raman active D- band and unusually suppressed conductivity mediated by nanoscale defects in pencil-lead graphitic systems under 80 keV Xe+ ion irradiation

Abstract

The effect of 80 keV Xe+ ion irradiation on the Raman spectra and electrical conductivity of 10B pencil-lead graphitic systems is being reported. The creation of localized nanoscale defects and a nearly five-fold improvement in the root mean square (RMS) roughness have been ascertained through atomic force microscopy (AFM) imaging studies. The introduction of defects is also substantiated by the appearance of the ∼1360 cm−1 peak (D-mode) along with the fundamental G-band (∼1600 cm−1) in the Raman spectra. With increasing fluence, the D-to-G band intensity ratio offered an increasing trend up to ∼0.44. Moreover, I–V characteristics indicated a significant drop in the conductivity of the irradiated graphitic systems. We ascribe it to substantial lowering of the mobility of the electrons owing to enhanced carrier-defect scattering events occurring in the irradiated systems. Mediated by defects introduced, a clear connection between the Raman characteristics and carrier transport phenomena is established.