(a) Time traces of transmitted terahertz electric field through 7.6 nm (red) and 8.2 nm (green) thick gold films on Si substrates and through bare Si substrate as a reference. Solid line and dotted line represent MPTMS-coated samples and uncoated samples respectively. (b) The corresponding Fourier-transformed amplitudes (left) and phases (right). Real (c) and imaginary (d) part of conductivity for ultra-thin gold films having different thicknesses. The data clearly reveal that the MPTMS-coated films (solid line) have enhanced conductivity than uncoated films (dotted line) at same thickness.