Terahertz radiation (THz) from the surfaces of various semiconductor wafers and inicrostructures is studied. The intensities of THz radiation from the surfaces of certain semiconductors with a thin layer of conjugate polymer [2, 3-dibutoxy- 1, 4-poly(phenylene vinylene)] deposited on their surfaces is greatly enhanced. The enhancement of THz radiation depends on the mechanism used to induct the THz radiation. Modulation spectroscopy of photoreflectance is employed to investigate the change in the built-in electric field and surface or interface state densities, which are closely related to the enhancement of the THz radiation. (c) 2008 The Electrochemical Society.