New Optical Method for Studying Defects in Silicon.

摘要

A new optical method incorporating two monochromatic light beams incident on the sample whose temperature is approximately at 78 K is used to study infrared active radiation-induced defect absorption bands. Defect energy levels, photoionization excitation and deexcitation processes were examined for the divacancy associated bands found in the 3 - 3.6 micrometers wavelength region and two higher order bands which appear in the 7 to 14 micrometers wavelength region. For the divacancy band region 10 Ohm-cm and 0.1 Ohm-cm n-type (P-doped) crucible grown silicon irradiated to 5 x 10 to the 18th power neutrons/sq cm (E > 1 MeV) were examined. An excitation energy (E sub e) of width 0.81eV to 0.89eV was found to produce an absorption throughout the entire 3.3 micrometers absorption band region with a maximum absorption occurring around 3.1 micrometers. A model is proposed which incorporates direct band gap transitions. A 200 Ohm-cm p-type (B-doped) crucible grown silicon sample irradiated to 5 x 10 to the 18th power neutrons/sq cm (E > 1 MeV) and annealed at 500 degrees for 15 minutes was examined for higher order bands. The 9.54 micrometers and 9.08 micrometers bands were found to have a maximum absorption for band gap energy. a model is proposed for the photoionization process incorporating the band gap energy for absorption and a depletion energy of 0.74eV. (Author)