Regrowth characteristics of SiGe/Si by IBIEC and SPEG

Single crystalline Si1−xGex/Si with three kinds of Ge contents (x: 0.05, 0.1, and 0.2) with thicknesses of 400-440 nm were amorphized by 500 keV (x: 0.05 and 0.1) and 600 keV (x: 0.2) Ge ion beam bombardment to a fluence of 1.0 × 1016 ions/cm2 at room temperature. The regrowth behavior of the damaged layers were compared between ion beam induced epitaxial crystallization (IBIEC) by 2.0 MeV Ge ions at 300 °C to fluences of 1.0-3.0 × 1016 ions/cm2 and solid phase epitaxial growth (SPEG) carried out in a flowing N2 ambient for up to 40 min at 600 °C. Rutherford backscattering spectroscopy (RBS) with channeling techniques revealed that crystallinity improvement by IBIEC tended to be saturated with increasing fluence while crystallinity improvement by SPEG was proceeded with increasing annealing time and relatively high quality SiGe layers were obtained. Crystallinity improvement was more rapid and pronounced for SiGe with higher Ge concentration both in IBIEC and SPEG. In contrast to the case of SPEG at 600 °C, transmission electron microscope (TEM) image in SiGe treated by IBIEC showed that bunches of dislocation loops remained as islands surrounded by single crystalline lattice layers image, leading to the high RBS aligned yield even after completion of the layer-by-layer regrowth.