EPITAXIAL-GROWTH VERSUS NUCLEATION IN AMORPHOUS SI DOPED WITH CU AND AG

The competition between solid phase epitaxy and random nucleation in amorphous Si implanted with Cu and Ag has been studied. At low metal concentrations, solid phase epitaxy proceeds with slight deviations from the intrinsic rate, with the impurity segregated and evenly distributed in the amorphous layer. At an impurity concentration of 0.12 at. %, rapid nucleation occurs, transforming the remaining layer into polycrystalline Si. The nucleation rate is greater-than-or-equal-to 10(8) the intrinsic homogeneous rate. The effects of the metals on epitaxy scale with the amount of metal-Si interaction. Nucleation appears to occur when the metal impurities exceed their absolute solubility limit and begin to phase separate.