Optical and electrical characterization of 2D semiconducting graphitic carbon nitride by terahertz time-domain spectroscopy

In this report, the structural, morphological and electro-optical analysis of 2-D graphitic carbon nitride (g-C₃N₄) nano-sheets has been performed. The g-C₃N₄ nano-sheets were synthesized based on the thermal calcination process and characterized by transmission electron microscopy (TEM). X-ray diffraction studies (XRD) showed the inter-layer spacing to be 0.323 nm for the (002) plane which is 3.5% more dense than crystalline graphite and higher than literature reports for g-C₃N₄. For the evaluation of electro-optical properties, we have utilized time-domain spectroscopy for the frequency range 0.2 to 2 THz. The complex reflective indices (n, k) and permittivity (\(\epsilon , \epsilon {\prime})\) for g-C₃N₄ have been determined. The complex conductivity has been observed to increase monotonically with an increase in frequency. The mobility of g-C₃N₄ has been theoretically estimated. The terahertz band properties such as plasma frequency, damping rate (0.095 THz), and collision time, were calculated for the synthesized material. The high permittivity value for g-C₃N₄ as reported in this work is promising for THz frequency selective components such as resonators, absorbers and collimators.