Irradiation-induced defect states in epitaxial n-type Si1-xGex alloy layers

Relaxed n-type Si1-xGex layers with 0 less than or equal to x less than or equal to 0.25 of high structural and electrical quality grown by molecular-beam epitaxy on (100) Si substrates using the compositional grading technique were irradiated with 2-MeV protons or low-energy ions. Four peaks were observed in the deep-level transient spectroscopy spectra after proton irradiation. The dominating line has been identified as originating from the Sb vacancy pair. Although the activation enthalpy of this line is observed to increase with increasing Ge content, its energy level relative to the conduction-band edge is the same for all compositions.