Fig. 3: Molecular defect and THz-wave absorption.

a Curve fittings of C 1s core-level spectra before and after annealing. The chemical state of CH3NH2 molecular defect is observed clearly. The C-O chemical state originated from the exposure to air during the sample transfer and b THz-TDS measurements with three absorptions at 0.8, and 1.4, and 2.0 THz. The PA (1/cm) is close to 2000.