Phonon-assisted transitions to a temperature-independent deep level in Co–Si

Abstract

Photoconductivity has been studied in p-type and high-resistivity n-type silicon compensated by cobalt. Threshold energies of 0.505, 0.537, and 0.572 eV are observed to be independent of temperature within the experimental accuracy of ±2 meV. This is the first direct experimental evidence of the temperature independence of a deep level in Si. The photoconductivity which is stronger for p-type samples than for n type leads to its identification as a new deep level 0.521 eV ±2 meV from the valence band; the phototransitions are phonon assisted.