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

The segregation of phosphorus and germanium to grain boundaries in P implan ted, Si0.87Ge0.13 films deposited by chemical vapor deposition (CVD), was i nvestigated using energy dispersive x-ray (EDX) micro-analysis. A quantitat ive 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 activat ion energy of 0.28 eV. On the other hand, Ge did not segregate to grain bou ndaries 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.