Segregation of phosphorus and germanium to grain boundaries in chemical vapor deposited silicon-germanium films determined by scanning transmission electron microscopy

Abstract

The segregation of phosphorus and germanium to grain boundaries in P implanted, Si0.87Ge0.13 films deposited by chemical vapor deposition (CVD), was investigated using energy dispersive x-ray (EDX) micro-analysis. A quantitative analysis of the x-ray spectra obtained at grain boundaries showed that the excess amount of P varied with the crystallography of the boundary but that the segregation always followed an equilibrium process with an activation energy of 0.28 eV. On the other hand, Ge did not segregate to grain boundaries in either P implanted Si0.87Ge0.13 films nor in intrinsic Si1−xGex films, containing 2, 13 and 31 at.% Ge. Possible reasons for the absence of Ge segregation are discussed.