Some characteristics of the crystalline-amorphous threshold point of 31P+ ion-implanted silicon substrates

During ion implantation a stage can be reached in which a continuous layer within the implanted crystal changes into amorphous material. The change begins when the implanted dose attains a certain threshold value (D_T). In-situ reflectivity (R) versus dose (D) measurements, made during the implantation of ³¹P⁺ into Si single crystal substrates showing that both D_T and the work (W_oT) required to induce the threshold conditions within the implanted crystal increase with the implantation energy are reported. It is also shown that the change in reflectivity ΔR_i, which occurs in the dose range that contains D_T, is a function of E and peaks at 140 keV, the energy at which the damaged layer becomes buried. The ratio D_A/D_T is found to be a decreasing function of E