A scanning near-field microscope provides nano-scale imaging capability of field induced THz wave emission spectra from semiconductor surfaces and interfaces. Combined with a scanning probe tip and femtosecond optical pulse excitation, THz wave emission with sub-100 nm spatial resolution has been demonstrated. The scanning probe tip modulates semiconductor surface field with nano-scale accuracy through the imaging charge dipole, the tunneling current, or the contact current. The modulated THz wave from the highly localized area under the scanning tip is detected in time-domain. This aperture-less imaging method leads the way to study nano-scale to atomic level emission spectroscopy at THz frequency range.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.