Si(001) epitaxy from hyperthermal beams: Crystal growth, doping, and electronic properties

Epitaxial undoped and Sb-doped Si films have been grown on Si(001) substrates at temperatures T_s between 80 and 750°C using hyperthermal Si (average energy 〈E_Si〉 ≃ 18 eV) and Sb (〈E_Sb〉 ≃ 14 eV) beams generated by ultra high vacuum Kr⁺ ion-beam sputtering. Critical epitaxial thicknesses t_e in undoped films were found to range from 8 nm at T_s = 80°C to > 1.2 μm at T_s ≥ 300°C while Sb incorporation probabilities σ_Sb varied from unity at T_s ≲ 550°C to ≃ 0.1 at 750°C. These t_e and σ_Sb values are approximately one and one-to-three orders of magnitude, respectively, higher than reported results achieved with molecular-beam epitaxy. Temperature-dependent transport measurements carried out on 1 μm-thick Sb-doped layers grown at T_s ≥ 350°C showed that Sb was incorporated into substitutional sites with complete electrical activity and that electron mobilities in films grown at T_s ≥ 400°C were equal to the best reported results for bulk Si.