Dopant effects on solid phase epitaxy in silicon and germanium

Abstract

The kinetics of dopant-enhanced solid phase epitaxy (SPE) are studied in amorphous silicon (a-Si) and germanium (a-Ge) layers formed by ion implantation. Implanted Sb dopants into a-Ge up to a concentration of 1 × 1020 cm−3 are considered and compared to As implanted layers at similar concentrations. Although an active Sb concentration above the solubility limit is achieved, a significant portion of the implanted atoms are not. P, As, and B enhanced SPE rates in Si from the literature are also considered. The relative velocities of P and As in Si is similar to that of As and Sb in Ge. Theoretical predictions using a simple form of the generalized Fermi level shifting model, which incorporates both dopant and dopant-induced stress effects, is shown to agree well with the data. A single set of two parameters are determined, which describe the dopant enhanced SPE data well independent of dopant species and concentration.