Substantial reduction of defects in silicon-on-sapphire material is required to broaden the range of applications to include bipolar devices. During the past few years, it has been shown that regional amorphization of the silicon layer by implantation of silicon and solid phase epitaxy regrowth can reduce the defect density in the silicon overlayer. However, one obstacle to large scale use of this process is that it requires implantation of silicon-29 ions to avoid introduction of contaminants. Another obstacle is that the wafers must be cooled to liquid nitrogen temperature. This program will study the effect of a germanium implantation and solid phase epitaxy process which could be feasible for large scale wafer improvement. Implantation of germanium is advantageous because amorphization can be achieved with a dose almost an order of magnitude lower than required with silicon and without liquid nitrogen cooling.
