Impact of high energy particle irradiation on the electrical performance of Si1-xGex epitaxial diodes

The impact of 20-MeV alpha ray irradiation on the electrical characteristic s of strained-layer epitaxial Si1-xGex diodes is investigated as a function of fluence and Ge content (x = 0.08, 0.12 and 0.16). The reverse current a t a fixed bias increases with fluence, although the rate of increase decrea ses with increasing fluence and/or Ge content. The reduction of the capacit ance with fluence points to a strong deactivation of the boron (B) dopant a toms, which decreases with increasing Ge content. The close to square root dependence between the B-deactivation and the reverse current increase, sug gests that in the irradiated diodes the latter is dominated by deep levels associated with interstitial B complexes. This is confirmed by deep level t ransient spectroscopy, revealing that the trap introduction rate at a given fluence reduces with increasing Ge content, similar to that for the revers e diode current.