Visible interference effects in silicon caused by high-current–high-dose implantation

Silicon samples with visible color bands have been produced by high beam currents and have been studied using optical reflectivity, Rutherford backscattering (channeling), and transmission electron microscopy. Backscattering shows crystalline or near-crystalline layers at the surface, buried amorphous layers centered at the damage range, and a deeper damage peak. Complex interference spectra are successfully analyzed for two sets of fringes: a visible set primarily associated with the crystalline layer of index of refraction nx at the surface and an infrared set primarily associated with the buried amorphous layer (na≳nx). Interband transitions in the ultraviolet confirm the existence of crystalline layers at the surface. The deeper damage peak is composed of small dislocations as shown by electron microscopy.