Carbon-related defects in proton-irradiated, n-type epitaxial Si1-xGex

C-i and CiCs defects, created by proton irradiation of n-type, strain-relax ed, epitaxial Si1-xGex of 0.005 less than or equal to x less than or equal to 0.5, have been studied using deep-level transient spectroscopy (DLTS). T he ionization enthalpies of the two defects relative to the conduction band edge, Delta H, are found to increase linearly with increasing Ge content. It is shown that the corresponding levels are not pinned to any of the band edges. Furthermore, it is shown that, for both defects, the slopes, delta Delta H/delta x, as well as the full width at half maximum (FWHM) of the co rresponding DLTS peaks, are similar. These observations are in agreement wi th conclusions deduced from previous electron-paramagnetic resonance (EPR) measurements in pure silicon, stating that, for both defects, the trapped e lectron is preferentially located at the C-i atom because of its larger ele ctronegativity as compared to those of silicon and germanium. The anneal te mperature of the C-i defect, and correspondingly the in-growth temperature of the CiCs complex, increase with increasing Ge content. This is equivalen t to an increasing retardation of the diffusion of C-i in Si1-xGex with inc reasing Ge content. (C) 1999 American Institute of Physics. [S0003-6951(99) 00652-X].