The effect of stress on the luminescence spectrum of irradiated silicon

Silicon crystals which have been irradiated with neutrons, high energy electrons, or gamma-rays at room temperature show two strong luminescence bands in the near infrared. Both bands have a sharp zero-phonon line followed by a series of broad phonon assisted peaks. The higher energy band associated with a zero-phonon line at 0.97 eV is independent of any impurities while the lower energy band with a zero-phonon line at 0.79 eV is seen only in silicon containing oxygen. Data on the temperature and stress dependence of the luminescence bands have been taken in order to obtain information on the type of defects and the optical transitions involved. The narrow line widths observed for the zerophonon lines show that the transitions do not involve a free carrier. The zerophonon broadening and the major phonon assisted structure can be related to interactions with the momentum conserving transverse acoustical phonons. The energies and form of the bands do not fit the usual mechanisms involving an exciton bound to a neutral or ionized donor or acceptor. An exciton bound to a neutral defect which has a trapping level nearly as deep as the binding energy determined from the luminescence is a possible mechanism. The zero-phonon line at 0.79 eV is a doublet showing thermal pbpulation effects which relate it to two levels in the initial state. The lack of any association with impurities, the annealing, and the stress data for the bands associated with the 0.97 eV zero-phonon line all support an identification of these bands, with the divacancy. The oxygen dependence and the thermal stability of the bands associated with the 0.79 eV zero-phonon line lead to a tentative identification of these bands with the K-center or G-15 center seen in EPR. A model for this defect which was tentatively suggested by the EPR investigators consists of two nearest neighbor substitutional oxygen atoms in a [221] crystal orientation. The stress data are not completely explained by this model and a [lOO] defect model would also fit the stress splitting.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Jones, Colin Elliott

Contributors dc:contributor

• Compton, W.D.

• luminescence spectrum
• irradiated silicon
• silicon crystals
• stress dependence

Statement dc:rights

• 1970 Colin Elliott Jones

Language dc:language

en

Identifier

6054238

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/25858