Nanocrystals of group-IV semiconductor materials (Si, Ge, and SiGe) have been fabricated in SiO2 by ion implantation and subsequent thermal annealing. The microstructure of these nanocrystals has been studied by transmission electron microscopy. Critical influences of the annealing temperatures and implantation doses on the nanocrystal size distributions are demonstrated with the Ge-implanted systems. Significant roughening of the nanocrystals occurs when the annealing temperature is raised above the melting temperature of the implanted semiconductor material.

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Solid phase epitaxy of 3500-Å-thick GexSi1−x (0.04≤x≤0.12) films on (100) Si substrates has been investigated. The thickness of regrown layers increased linearly with annealing time in the temperature range of 475–575 °C. The regrowth rates of stressed alloys were less than those of pure Si, while stress-relaxed alloys have larger rates than Si. The difference in regrowth rates was explained by the activation-strain tensor model (Aziz, Sabin, and Lu, to be published in Phys. Rev. B). The first element of the activation-strain tensor obtained in this experiment was in excellent agreement with that deduced by Aziz et al. For low Ge concentrations (x<0.08), the recrystallized region was of good crystalline quality. However, threading dislocations were observed in a stressed Ge0.1Si0.9 alloy after complete recrystallization. During the regrowth at 550 °C, the Ge-Si alloy first regrew coherently up to 300 Å, above which threading dislocations started to nucleate. On the other hand, no dislocations were detected in the regrown layer of a stress-relaxed Ge0.1Si0.9 alloy sample.

Addition of the organogermanium compound, Me3GeS(CH2)3Si(OMe)3, to a modified, conventional sol−gel formulation gives a silica xerogel doped with this molecular species. Subsequent thermal treatment of this molecularly doped xerogel under oxidizing then reducing conditions affords nanoclusters of Ge highly dispersed throughout the bulk of the xerogel matrix. Under appropriate conditions, Ge nanoclusters having an average diameter of ca. 68 Å can be formed by this procedure. Characterization of this nanocomposite material by TEM, HRTEM, EDS, XRD, micro-Raman spectroscopy, electron diffraction, and UV−visible spectroscopy indicates that the Ge nanoclusters are highly crystalline and exhibit optical properties consistent with those expected when quantum confinement effects are operative.