Study of the band-gap energy of radiation-damaged silicon

The transmission of silicon crystals irradiated by 24 GeV/c protons and reactor neutrons has been measured for photon energies, E-gamma, between 0.95 and 1.3 eV. From the transmission data the absorption coefficient alpha is calculated, and from alpha(E-gamma) the fluence dependence of the band-gap energy, E-gap, and the energy of transverse optical phonons, E-ph, determined. It is found that within the experimental uncertainties of about 1 meV neither E-gap nor E-ph depend on fluence up to the maximum fluence of 1 x 10(17) cm(-2) of the measurements. The value of E-gap agrees within about 1 meV with the generally accepted value, if an exciton-binding energy of 15 meV is assumed. A similar agreement is found for E-ph. For the extraction of E-gap and E-ph the second derivative of root alpha(E gamma) smoothed with a Gaussian kernel has been used.

Automated summary

The transmission of silicon crystals irradiated by protons and reactor neutrons was measured for photon energies between 0.95 and 1.3 eV. The results show that the band-gap energy and the energy of transverse optical phonons remain stable regardless of the fluence, and are consistent with the generally accepted values.