Optical reflectance of germanium surface modified by implanted silver ions

© 2020 Elsevier B.V. The article focuses on the optical reflection from the surface of the Ge substrates implanted with Ag+ ions at the low energy of 30 keV and the dose range from 5.0⋅1014 to 1.5⋅1017 ion/cm2. The optical findings were compared with the electron microscopy observations. The study showed that if the ion radiation dose increases, the reflection intensity monotonously decreases in the ultraviolet and visible spectral regions from virgin Ge surface. This occurs due to amorphization if the doses are low and due to formation of nanoporous structure of interwoven nanowires in the near-surface implanted Ge layer for the higher doses. According to the Mie theory modeling of optical scattering by nanostructured Ge shows a qualitative agreement between the calculated and experimental spectra