Double solid phase epitaxy of germanium implanted silicon on sapphire

Germanium-implanted double solid phase epitaxial (DSPE) material was produced in 0.3-μm intrinsic silicon on sapphire. First, 4×10¹⁴ germanium ions/cm² were implanted at 320 keV in a nonaligned direction. This implantation amorphized the inner part of the silicon. The wafers were annealed at 550, 600, 700, 800, 900 or 1000°C. Next, 8×10¹⁴ germanium ions/cm ² were implanted at 100 keV. The implantation formed a 100-nm thick amorphous layer beneath the surface. This layer was epitaxially regrown from the inner part of the silicon crystal during the second annealing treatment, which was made at the same temperature as the first one for each wafer. Only a low number of implantation-induced carriers were formed in germanium-implanted intrinsic silicon on sapphire. Another advantage of using germanium for the amorphization is that the implantation dose can be reduced by more than 50% compared with silicon ions