High-quality crystalline Si1-xGex (x=0.10 and 0.25)
alloys were implanted with 70 keV Er+ ions at temperatures of
350°C and 550°C to a fluence of 1015 cm−2. In-situ
Rutherford backscattering/channeling (RBS) analysis supplemented with
transmission electron microscopy (TEM) showed that as-implanted alloys were
in form of ternary solid solutions with a peak Er concentration of 1 at.%
without any trace of Er-Si or Er-Ge precipitation.
In the samples implanted at 350°C Er atoms were found to be distributed
randomly in the amorphous host matrix. Post-implantation annealing at
different temperatures up to 600° showed that the solid phase epitaxial
regrowth of the damaged layers strongly depends on both the Ge concentration
in the alloys and the temperature of annealing. Along with the
recrystallization of the damaged matrix, annealing was observed to induce
simultaneous removal of nearly all the implanted Er as the recrystallization
front progresses towards the surface.
In contrast, high temperature implantation at 550°C led to spontaneous
recovery of the alloy crystallinity and incorporation of considerable
fraction of implanted Er atoms on regular tetrahedral interstitial sites in
the host lattice.