THE ROLE OF STRAIN IN THE CRYSTALLIZATION OF GE IMPLANTED (100) SI

The effect of strain on the epitaxial crystallisation of Ge implanted (100) Si has been investigated. Crystallisation kinetics were monitore d using in situ time-resolved reflectivity (TRR), whilst post-anneal d efect distributions were measured by Rutherford backscattering and cha nnelling spectrometry (RBS-C) and transmission electron microscopy (TE M). It is shown that for fluences above a critical value strain-relaxa tion occurs during crystallisation at a depth determined by the Ge flu ence. Strain relaxation is accompanied or preceded by a roughening of the crystalline/amorphous interface and a reduction in the crystallisa tion velocity. Continued crystallisation in the strain-relaxed materia l then leads to a reduction in interface roughness and an increase in velocity, suggesting a correlation between strain and interface roughn ess. Preliminary results are also reported for ion-beam-annealed alloy layers. For thin alloy layers, less-than-or-equal-to 100 nm, ion-beam induced epitaxial crystallisation (IBIEC) is shown to produce epitaxi al alloy layers of high crystalline quality, however, for thick GeSi a lloy layers, less-than-or-equal-to 800 nm, IBIEC competes with ion-bea m induced random crystallisation.