New Optical Method for Studying Defects in Silicon
ARMY MILITARY PERSONNEL CENTER ALEXANDRIA VA
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A new optical method incorporating two monochromatic light beams incident on the sample whose temperature is at approx. 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 micron wavelength region and two higher order bands which appear in the 7 to 14 micron wavelength region. For the divacancy band region 100hms-cm and 0.10hm-cm n-type P-doped crucible grown silicon irradiated to 5 x 10 to the 18th power neutronssq 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 micron absorption band region with a maximum absorption occurring around 3.1 micron. A model is proposed which incorporates direct band gap transitions. A 200ohm-cm p-type B- doped crucible grown silicon sample irradiated to 5 x 10 to the 18th power neutronssq cm E 1 MeV and annealed at 500 C for 15 minutes was examined for higher order bands. The 9.54 micron and 9.08 micron 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.
- Solid State Physics